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Incorrect floating point values when using GHC API

Summary

On an M1 Mac, floating point literals are interpreted incorrectly by the GHC API when using compileExpr. For instance (full code further below):

    let chck = "5.5626902089526504e-303 :: Double"
    v <- compileExpr chck
    print (unsafeCoerce v :: Double)

prints

6.213763703753626e-303

On the Haskell discourse, other users with ARM processors have reported getting the correct behavior (not seeing this bug): https://discourse.haskell.org/t/different-results-from-ghc-api-and-ghci/10988/8

Steps to reproduce

On my (presumably any) M1 Mac, using GHC 9.6.6, 9.8.4, and 9.10.1, the below code:

module Main where

import GHC
import GHC.Paths
import Unsafe.Coerce
import Control.Monad.IO.Class


main :: IO ()
main = do
    runGhc (Just libdir) (do
        dyn_flags <- getSessionDynFlags
        _ <- setSessionDynFlags dyn_flags

        setContext [ IIDecl . simpleImportDecl . mkModuleName $ "Prelude"
                   , IIDecl . simpleImportDecl . mkModuleName $ "Unsafe.Coerce" ]
        
        wrong)

wrong :: Ghc ()
wrong = do
    let chck = "5.5626902089526504e-303 :: Double"
    v <- compileExpr chck

    liftIO $ do
        putStr "Direct: "
        print (5.5626902089526504e-303 :: Double)
        putStr "API:    "
        print (unsafeCoerce v :: Double)

    let chck2 = "5.56269020895265e-303 :: Double"
    v2 <- compileExpr chck2

    liftIO $ do
        putStr "Direct: "
        print (5.56269020895265e-303 :: Double)
        putStr "API:    "
        print (unsafeCoerce v2 :: Double)

outputs:

Direct: 5.5626902089526504e-303
API:    6.213763703753626e-303
Direct: 5.56269020895265e-303
API:    5.2321149654365974e-303

Notice that something about going through compileExpr turns 5.5626902089526504e-303 into 6.213763703753626e-303, and 5.56269020895265e-303 into 5.2321149654365974e-303.

C Compiler + building and running:

billhallahan@Bills-MacBook-Pro-2 APITest % cc -v
Apple clang version 14.0.3 (clang-1403.0.22.14.1)
Target: arm64-apple-darwin22.1.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin
billhallahan@Bills-MacBook-Pro-2 APITest % cabal build
Resolving dependencies...
Build profile: -w ghc-9.10.1 -O1
In order, the following will be built (use -v for more details):
 - APITest-0.1.0.0 (exe:APITest) (first run)
Configuring executable 'APITest' for APITest-0.1.0.0...
Warning: [unknown-file] The 'license-file' field refers to the file 'LICENSE'
which does not exist.
Preprocessing executable 'APITest' for APITest-0.1.0.0...
Building executable 'APITest' for APITest-0.1.0.0...
Glasgow Haskell Compiler, Version 9.10.1, stage 2 booted by GHC version 9.6.2
*** initializing unit database:
package flags [-package-id base-4.20.0.0-380b{unit base-4.20.0.0-380b True ([])},
               -package-id ghc-9.10.1-64dd{unit ghc-9.10.1-64dd True ([])},
               -package-id ghc-pths-0.1.0.12-5ab02b64{unit ghc-pths-0.1.0.12-5ab02b64 True ([])}]
loading package database /Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/package.conf.d
loading package database /Users/billhallahan/.cabal/store/ghc-9.10.1-64dd/package.db
loading package database /Users/billhallahan/Documents/APITest/dist-newstyle/packagedb/ghc-9.10.1
loading package database /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/package.conf.inplace
wired-in package ghc-prim mapped to ghc-prim-0.11.0-e020
wired-in package ghc-bignum mapped to ghc-bignum-1.3-09c4
wired-in package ghc-internal mapped to ghc-internal-9.1001.0-4685
wired-in package base mapped to base-4.20.0.0-380b
wired-in package rts mapped to rts-1.0.2
wired-in package template-haskell mapped to template-haskell-2.22.0.0-e0ca
wired-in package ghc-experimental mapped to ghc-experimental-0.1.0.0-2008
!!! initializing unit database: finished in 12.64 milliseconds, allocated 2.335 megabytes
*** Chasing dependencies:
Chasing modules from: APITest-0.1.0.0-inplace-APITest:app/Main.hs
!!! Chasing dependencies: finished in 1.16 milliseconds, allocated 2.182 megabytes
Ready for upsweep
  [SingleModule(APITest-0.1.0.0-inplace-APITest:Main [])]
compile: input file app/Main.hs
*** Checking old interface for Main (use -ddump-hi-diffs for more details):
[1 of 1] Compiling Main             ( app/Main.hs, /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp/Main.o )
*** Parser [Main]:
!!! Parser [Main]: finished in 0.37 milliseconds, allocated 1.086 megabytes
*** Renamer/typechecker [Main]:
!!! Renamer/typechecker [Main]: finished in 133.67 milliseconds, allocated 121.107 megabytes
*** Desugar [Main]:
Result size of Desugar (before optimization)
  = {terms: 338, types: 284, coercions: 11, joins: 0/8}
*** Core Linted result of Desugar (before optimization):
Result size of Desugar (after optimization)
  = {terms: 227, types: 182, coercions: 4, joins: 0/0}
*** Core Linted result of Desugar (after optimization):
!!! Desugar [Main]: finished in 1.10 milliseconds, allocated 2.450 megabytes
*** Simplifier [Main]:
Result size of Simplifier iteration=1
  = {terms: 491, types: 567, coercions: 584, joins: 0/16}
*** Core Linted result of Simplifier:
Result size of Simplifier iteration=2
  = {terms: 415, types: 469, coercions: 255, joins: 0/6}
*** Core Linted result of Simplifier:
Result size of Simplifier iteration=3
  = {terms: 397, types: 439, coercions: 215, joins: 0/2}
*** Core Linted result of Simplifier:
Result size of Simplifier iteration=4
  = {terms: 393, types: 435, coercions: 215, joins: 0/0}
*** Core Linted result of Simplifier:
Result size of Simplifier
  = {terms: 393, types: 435, coercions: 215, joins: 0/0}
*** Core Linted result of Simplifier:
!!! Simplifier [Main]: finished in 49.26 milliseconds, allocated 66.224 megabytes
*** Specialise [Main]:
Result size of Specialise
  = {terms: 393, types: 435, coercions: 215, joins: 0/0}
*** Core Linted result of Specialise:
!!! Specialise [Main]: finished in 0.64 milliseconds, allocated 1.591 megabytes
*** Float out(FOS {Lam = Just 0,
                   Consts = True,
                   OverSatApps = False}) [Main]:
Result size of Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False})
  = {terms: 547, types: 630, coercions: 215, joins: 0/0}
*** Core Linted result of Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = False}):
!!! Float out(FOS {Lam = Just 0,
                   Consts = True,
                   OverSatApps = False}) [Main]: finished in 1.05 milliseconds, allocated 2.226 megabytes
*** Simplifier [Main]:
Result size of Simplifier iteration=1
  = {terms: 421, types: 465, coercions: 215, joins: 0/0}
*** Core Linted result of Simplifier:
Result size of Simplifier
  = {terms: 421, types: 465, coercions: 215, joins: 0/0}
*** Core Linted result of Simplifier:
!!! Simplifier [Main]: finished in 2.10 milliseconds, allocated 5.122 megabytes
*** Simplifier [Main]:
Result size of Simplifier iteration=1
  = {terms: 465, types: 517, coercions: 252, joins: 0/0}
*** Core Linted result of Simplifier:
Result size of Simplifier
  = {terms: 459, types: 508, coercions: 252, joins: 0/0}
*** Core Linted result of Simplifier:
!!! Simplifier [Main]: finished in 5.03 milliseconds, allocated 9.488 megabytes
*** Simplifier [Main]:
Result size of Simplifier iteration=1
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Simplifier:
Result size of Simplifier
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Simplifier:
!!! Simplifier [Main]: finished in 2.90 milliseconds, allocated 5.515 megabytes
*** Float inwards [Main]:
Result size of Float inwards
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Float inwards:
!!! Float inwards [Main]: finished in 0.45 milliseconds, allocated 1.475 megabytes
*** Called arity analysis [Main]:
Result size of Called arity analysis
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Called arity analysis:
!!! Called arity analysis [Main]: finished in 0.50 milliseconds, allocated 1.485 megabytes
*** Simplifier [Main]:
Result size of Simplifier
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Simplifier:
!!! Simplifier [Main]: finished in 0.86 milliseconds, allocated 2.472 megabytes
*** Demand analysis (including Boxity) [Main]:
Result size of Demand analysis (including Boxity)
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Demand analysis (including Boxity):
!!! Demand analysis (including Boxity) [Main]: finished in 164.39 milliseconds, allocated 180.421 megabytes
*** Constructed Product Result analysis [Main]:
Result size of Constructed Product Result analysis
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Constructed Product Result analysis:
!!! Constructed Product Result analysis [Main]: finished in 0.44 milliseconds, allocated 1.293 megabytes
*** Worker Wrapper binds [Main]:
Result size of Worker Wrapper binds
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Worker Wrapper binds:
!!! Worker Wrapper binds [Main]: finished in 0.40 milliseconds, allocated 1.255 megabytes
*** Simplifier [Main]:
Result size of Simplifier
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Simplifier:
!!! Simplifier [Main]: finished in 0.96 milliseconds, allocated 2.491 megabytes
*** Exitification transformation [Main]:
Result size of Exitification transformation
  = {terms: 467, types: 510, coercions: 252, joins: 0/0}
*** Core Linted result of Exitification transformation:
!!! Exitification transformation [Main]: finished in 0.40 milliseconds, allocated 1.210 megabytes
*** Float out(FOS {Lam = Just 0,
                   Consts = True,
                   OverSatApps = True}) [Main]:
Result size of Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = True})
  = {terms: 501, types: 531, coercions: 252, joins: 0/0}
*** Core Linted result of Float out(FOS {Lam = Just 0, Consts = True, OverSatApps = True}):
!!! Float out(FOS {Lam = Just 0,
                   Consts = True,
                   OverSatApps = True}) [Main]: finished in 0.68 milliseconds, allocated 2.065 megabytes
*** Common sub-expression [Main]:
Result size of Common sub-expression
  = {terms: 493, types: 531, coercions: 249, joins: 0/0}
*** Core Linted result of Common sub-expression:
!!! Common sub-expression [Main]: finished in 3.27 milliseconds, allocated 1.759 megabytes
*** Float inwards [Main]:
Result size of Float inwards
  = {terms: 493, types: 531, coercions: 249, joins: 0/0}
*** Core Linted result of Float inwards:
!!! Float inwards [Main]: finished in 0.47 milliseconds, allocated 1.526 megabytes
*** Simplifier [Main]:
Result size of Simplifier iteration=1
  = {terms: 461, types: 509, coercions: 252, joins: 0/0}
*** Core Linted result of Simplifier:
Result size of Simplifier
  = {terms: 461, types: 509, coercions: 252, joins: 0/0}
*** Core Linted result of Simplifier:
!!! Simplifier [Main]: finished in 1.77 milliseconds, allocated 4.952 megabytes
*** Demand analysis [Main]:
Result size of Demand analysis
  = {terms: 461, types: 509, coercions: 252, joins: 0/0}
*** Core Linted result of Demand analysis:
!!! Demand analysis [Main]: finished in 1.41 milliseconds, allocated 2.957 megabytes
*** CoreTidy [Main]:
!!! CoreTidy [Main]: finished in 0.35 milliseconds, allocated 0.909 megabytes
Result size of Tidy Core
  = {terms: 461, types: 509, coercions: 252, joins: 0/0}
*** Core Linted result of Tidy Core:
Created temporary directory: /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22891_0
*** LatePlugins [Main]:
!!! LatePlugins [Main]: finished in 0.00 milliseconds, allocated 0.013 megabytes
*** CorePrep [Main]:
Result size of CorePrep
  = {terms: 511, types: 548, coercions: 252, joins: 0/11}
*** Core Linted result of CorePrep:
!!! CorePrep [Main]: finished in 0.65 milliseconds, allocated 1.757 megabytes
*** CoreToStg [Main]:
*** Stg2Stg:
!!! CoreToStg [Main]: finished in 1.56 milliseconds, allocated 0.880 megabytes
*** CodeGen [Main]:
!!! CodeGen [Main]: finished in 5.76 milliseconds, allocated 13.732 megabytes
*** WriteIface [/Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp/Main.hi]:
writeBinIface: 136 Names
writeBinIface: 368 dict entries
!!! WriteIface [/Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp/Main.hi]: finished in 0.74 milliseconds, allocated 1.437 megabytes
*** systool:as:
*** Assembler:
gcc '--target=arm64-apple-darwin' -Qunused-arguments -iquoteapp -I/Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp -I/Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp -I/Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/autogen -I/Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/global-autogen -I/Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp -fno-common -U__PIC__ -D__PIC__ -x assembler -c /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22891_0/ghc_1.s -o /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp/Main.o.tmp
!!! systool:as: finished in 1.04 milliseconds, allocated 0.187 megabytes
*** Deleting temp files:
Deleting: /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22891_0/ghc_1.s /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22891_0/ghc_2.c
Warning: deleting non-existent /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22891_0/ghc_2.c
*** Deleting temp subdirs:
Deleting: 
Upsweep completely successful.
*** Deleting temp files:
Deleting: 
*** Deleting temp subdirs:
Deleting: 
*** Deleting temp dirs:
Deleting: /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22891_0
Glasgow Haskell Compiler, Version 9.10.1, stage 2 booted by GHC version 9.6.2
*** initializing unit database:
package flags [-package-id base-4.20.0.0-380b{unit base-4.20.0.0-380b True ([])},
               -package-id ghc-9.10.1-64dd{unit ghc-9.10.1-64dd True ([])},
               -package-id ghc-pths-0.1.0.12-5ab02b64{unit ghc-pths-0.1.0.12-5ab02b64 True ([])}]
loading package database /Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/package.conf.d
loading package database /Users/billhallahan/.cabal/store/ghc-9.10.1-64dd/package.db
loading package database /Users/billhallahan/Documents/APITest/dist-newstyle/packagedb/ghc-9.10.1
loading package database /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/package.conf.inplace
wired-in package ghc-prim mapped to ghc-prim-0.11.0-e020
wired-in package ghc-bignum mapped to ghc-bignum-1.3-09c4
wired-in package ghc-internal mapped to ghc-internal-9.1001.0-4685
wired-in package base mapped to base-4.20.0.0-380b
wired-in package rts mapped to rts-1.0.2
wired-in package template-haskell mapped to template-haskell-2.22.0.0-e0ca
wired-in package ghc-experimental mapped to ghc-experimental-0.1.0.0-2008
!!! initializing unit database: finished in 11.29 milliseconds, allocated 2.335 megabytes
*** Chasing dependencies:
Chasing modules from: APITest-0.1.0.0-inplace-APITest:app/Main.hs
!!! Chasing dependencies: finished in 0.95 milliseconds, allocated 2.163 megabytes
Ready for upsweep
  [SingleModule(APITest-0.1.0.0-inplace-APITest:Main []),
   SingleModule(LN: [APITest-0.1.0.0-inplace-APITest:Main])]
compile: input file app/Main.hs
*** Checking old interface for Main (use -ddump-hi-diffs for more details):
[1 of 2] Skipping Main             ( app/Main.hs, /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp/Main.o )
*** Deleting temp files:
Deleting: 
*** Deleting temp subdirs:
Deleting: 
link: hmi ...
Main
link: linkables are ...
LinkableM (2024-12-13 17:50:24.92123009 UTC) Main
   [DotO /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp/Main.o]
link: pkg deps are ...
base
ghc-9.10.1-64dd
ghc-pths-0.1.0.12-5ab02b64
[2 of 2] Linking /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest
Created temporary directory: /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22948_0
*** systool:cc:
*** C Compiler:
gcc -c /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22948_0/ghc_1.c -o /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22948_0/ghc_2.o -fno-common -U__PIC__ -D__PIC__ -I/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/include/ffi -I/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/rts-1.0.2/include -Qunused-arguments '--target=arm64-apple-darwin'
!!! systool:cc: finished in 1.26 milliseconds, allocated 0.223 megabytes
*** systool:linker:
*** Linker:
gcc '--target=arm64-apple-darwin' -Qunused-arguments '--target=arm64-apple-darwin' -Wl,-no_fixup_chains -o /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest -lm /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest-tmp/Main.o -L/Users/billhallahan/.cabal/store/ghc-9.10.1-64dd/ghc-pths-0.1.0.12-5ab02b64/lib -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/ghc-9.10.1-64dd -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/semaphore-compat-1.0.0-e731 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/process-1.6.19.0-27d7 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/hpc-0.7.0.1-4943 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/ghci-9.10.1-bb28 -L/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/ghc-heap-9.10.1-e0ad -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/ghc-boot-9.10.1-d6fc -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/ghc-platform-0.1.0.0-36c7 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/directory-1.3.8.3-2b7f -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/unix-2.8.5.1-6d6f -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/time-1.12.2-c82d -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/filepath-1.5.2.0-a392 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/os-string-2.0.2-5a04 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/exceptions-0.10.7-b950 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/stm-2.5.3.1-9361 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/mtl-2.3.1-657d -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/transformers-0.6.1.1-ad7e -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/binary-0.8.9.2-ab44 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/containers-0.7-622f -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/bytestring-0.12.1.0-5f32 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/template-haskell-2.22.0.0-e0ca -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/pretty-1.1.3.6-1a72 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/ghc-boot-th-9.10.1-5379 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/deepseq-1.5.0.0-c88a -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/array-0.5.7.0-0e4b -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/base-4.20.0.0-380b -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/ghc-internal-9.1001.0-4685 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/ghc-bignum-1.3-09c4 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/ghc-prim-0.11.0-e020 -L/Users/billhallahan/.ghcup/ghc/9.10.1/lib/ghc-9.10.1/lib/../lib/aarch64-osx-ghc-9.10.1/rts-1.0.2 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-Wl,-u,_ghczminternal_GHCziInternalziIOziException_cannotCompactPinned_closure -Wl,-u,_ghczminternal_GHCziInternalziIOziException_cannotCompactMutable_closure -Wl,-u,_ghczminternal_GHCziInternalziIOPort_doubleReadException_closure -Wl,-u,_ghczminternal_GHCziInternalziControlziExceptionziBase_nonTermination_closure -Wl,-u,_ghczminternal_GHCziInternalziControlziExceptionziBase_nestedAtomically_closure -Wl,-u,_ghczminternal_GHCziInternalziEventziThread_blockedOnBadFD_closure -Wl,-u,_ghczminternal_GHCziInternalziConcziSync_runSparks_closure -Wl,-u,_ghczminternal_GHCziInternalziConcziIO_ensureIOManagerIsRunning_closure -Wl,-u,_ghczminternal_GHCziInternalziConcziIO_interruptIOManager_closure -Wl,-u,_ghczminternal_GHCziInternalziConcziIO_ioManagerCapabilitiesChanged_closure -Wl,-u,_ghczminternal_GHCziInternalziConcziSignal_runHandlersPtr_closure -Wl,-u,_ghczminternal_GHCziInternalziTopHandler_flushStdHandles_closure -Wl,-u,_ghczminternal_GHCziInternalziTopHandler_runMainIO_closure -Wl,-u,_ghczmprim_GHCziTypes_Czh_con_info -Wl,-u,_ghczmprim_GHCziTypes_Izh_con_info -Wl,-u,_ghczmprim_GHCziTypes_Fzh_con_info -Wl,-u,_ghczmprim_GHCziTypes_Dzh_con_info -Wl,-u,_ghczmprim_GHCziTypes_Wzh_con_info -Wl,-u,_ghczminternal_GHCziInternalziPtr_Ptr_con_info -Wl,-u,_ghczminternal_GHCziInternalziPtr_FunPtr_con_info -Wl,-u,_ghczminternal_GHCziInternalziInt_I8zh_con_info -Wl,-u,_ghczminternal_GHCziInternalziInt_I16zh_con_info -Wl,-u,_ghczminternal_GHCziInternalziInt_I32zh_con_info -Wl,-u,_ghczminternal_GHCziInternalziInt_I64zh_con_info -Wl,-u,_ghczminternal_GHCziInternalziWord_W8zh_con_info -Wl,-u,_ghczminternal_GHCziInternalziWord_W16zh_con_info -Wl,-u,_ghczminternal_GHCziInternalziWord_W32zh_con_info -Wl,-u,_ghczminternal_GHCziInternalziWord_W64zh_con_info -Wl,-u,_ghczminternal_GHCziInternalziStable_StablePtr_con_info -Wl,-u,_hs_atomic_add8 -Wl,-u,_hs_atomic_add16 -Wl,-u,_hs_atomic_add32 -Wl,-u,_hs_atomic_add64 -Wl,-u,_hs_atomic_sub8 -Wl,-u,_hs_atomic_sub16 -Wl,-u,_hs_atomic_sub32 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-lHSsemaphore-compat-1.0.0-e731 -lHSprocess-1.6.19.0-27d7 -lHShpc-0.7.0.1-4943 -lHSghci-9.10.1-bb28 -lHSghc-heap-9.10.1-e0ad -lHSghc-boot-9.10.1-d6fc -lHSghc-platform-0.1.0.0-36c7 -lHSdirectory-1.3.8.3-2b7f -lHSunix-2.8.5.1-6d6f -lHStime-1.12.2-c82d -lHSfilepath-1.5.2.0-a392 -lHSos-string-2.0.2-5a04 -lHSexceptions-0.10.7-b950 -lHSstm-2.5.3.1-9361 -lHSmtl-2.3.1-657d -lHStransformers-0.6.1.1-ad7e -lHSbinary-0.8.9.2-ab44 -lHScontainers-0.7-622f -lHSbytestring-0.12.1.0-5f32 -lHStemplate-haskell-2.22.0.0-e0ca -lHSpretty-1.1.3.6-1a72 -lHSghc-boot-th-9.10.1-5379 -lHSdeepseq-1.5.0.0-c88a -lHSarray-0.5.7.0-0e4b -lHSbase-4.20.0.0-380b -lHSghc-internal-9.1001.0-4685 -lHSghc-bignum-1.3-09c4 -lHSghc-prim-0.11.0-e020 -lHSrts-1.0.2 -liconv -lm -ldl -lffi -Wl,-dead_strip_dylibs -Wl,-headerpad,8000
!!! systool:linker: finished in 6.67 milliseconds, allocated 2.310 megabytes
*** otool:
otool -L /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest
*** otool:
otool -l /Users/billhallahan/Documents/APITest/dist-newstyle/build/aarch64-osx/ghc-9.10.1/APITest-0.1.0.0/x/APITest/build/APITest/APITest
link: done
Upsweep completely successful.
*** Deleting temp files:
Deleting: /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22948_0/ghc_1.c /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22948_0/ghc_3.rsp /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22948_0/ghc_4.rsp /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22948_0/ghc_2.o
*** Deleting temp subdirs:
Deleting: 
*** Deleting temp dirs:
Deleting: /var/folders/n8/29m6tzk94mzc6r_t6h42mc8m0000gn/T/ghc22948_0
billhallahan@Bills-MacBook-Pro-2 APITest % cabal run
Direct: 5.5626902089526504e-303
API:    6.213763703753626e-303
Direct: 5.56269020895265e-303
API:    5.2321149654365974e-303

Code, include Cabal file: APITest.zip

Expected behavior

I would expect the output:

Direct: 5.5626902089526504e-303
API:    5.5626902089526504e-303
Direct: 5.56269020895265e-303
API:    5.56269020895265e-303

Additional testing:

This appears to have something to do with the floats being written as literals. The below program, which uses hex encoding/encodeFloat, outputs correct results:

module Main where

import GHC
import GHC.Paths
import Unsafe.Coerce
import Control.Monad.IO.Class


main :: IO ()
main = do
    runGhc (Just libdir) (do
        dyn_flags <- getSessionDynFlags
        _ <- setSessionDynFlags dyn_flags

        setContext [ IIDecl . simpleImportDecl . mkModuleName $ "Prelude"
                   , IIDecl . simpleImportDecl . mkModuleName $ "Unsafe.Coerce" ]
        
        correct)

correct :: Ghc ()
correct = do
    let chck = "unsafeCoerce (0x012e848200000001 :: Integer) :: Double"
    v <- compileExpr chck

    liftIO $ do
        putStr "Direct: "
        print (unsafeCoerce (0x012e848200000001 :: Integer) :: Double)
        putStr "API:    "
        print (unsafeCoerce v :: Double)

    let chck2 = "encodeFloat 8589943181934593 (-1057) :: Double"
    v2 <- compileExpr chck2

    liftIO $ do
        putStr "Direct: "
        print (encodeFloat 8589943181934593 (-1057) :: Double)
        putStr "API:    "
        print (unsafeCoerce v2 :: Double)

Results:

Direct: 5.5626902089526504e-303
API:    5.5626902089526504e-303
Direct: 5.5626902089526504e-303
API:    5.5626902089526504e-303

Environment

  • GHC version used: 9.10.1 to get the above output (also tried 9.6.6 and 9.8.4, same incorrect printed results.)

Optional:

  • Operating System: MacOS Ventura 13.0
  • System Architecture: Apple M1 Max, ARM
billhallahan@Bills-MacBook-Pro-2 APITest % uname -a    
Darwin Bills-MacBook-Pro-2.local 22.1.0 Darwin Kernel Version 22.1.0: Sun Oct  9 20:15:09 PDT 2022; root:xnu-8792.41.9~2/RELEASE_ARM64_T6000 arm64
billhallahan@Bills-MacBook-Pro-2 APITest % cat /etc/motd
cat: /etc/motd: No such file or directory
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