From 86318ff9572a79819b02f9a79b855fa4d4a41df2 Mon Sep 17 00:00:00 2001
From: Luite Stegeman <stegeman@gmail.com>
Date: Thu, 12 Nov 2015 11:13:54 +0100
Subject: [PATCH] Change demand information for foreign calls
Foreign calls may not be strict for lifted arguments. Fixes Trac #11076.
Test Plan: ./validate
Reviewers: simonpj, bgamari, austin
Subscribers: thomie
Differential Revision: https://phabricator.haskell.org/D1464
GHC Trac Issues: #11076
---
compiler/basicTypes/MkId.hs | 5 ++++-
testsuite/tests/stranal/should_run/T11076.hs | 15 +++++++++++++
.../tests/stranal/should_run/T11076.stdout | 1 +
testsuite/tests/stranal/should_run/T11076A.hs | 21 +++++++++++++++++++
.../tests/stranal/should_run/T11076_prim.cmm | 10 +++++++++
testsuite/tests/stranal/should_run/all.T | 1 +
testsuite/tests/stranal/sigs/T8598.stderr | 2 +-
7 files changed, 53 insertions(+), 2 deletions(-)
create mode 100644 testsuite/tests/stranal/should_run/T11076.hs
create mode 100644 testsuite/tests/stranal/should_run/T11076.stdout
create mode 100644 testsuite/tests/stranal/should_run/T11076A.hs
create mode 100644 testsuite/tests/stranal/should_run/T11076_prim.cmm
diff --git a/compiler/basicTypes/MkId.hs b/compiler/basicTypes/MkId.hs
index c6161c52cda7..c3a9f9a7c82f 100644
--- a/compiler/basicTypes/MkId.hs
+++ b/compiler/basicTypes/MkId.hs
@@ -941,8 +941,11 @@ mkFCallId dflags uniq fcall ty
(_, tau) = tcSplitForAllTys ty
(arg_tys, _) = tcSplitFunTys tau
arity = length arg_tys
- strict_sig = mkClosedStrictSig (replicate arity evalDmd) topRes
+ strict_sig = mkClosedStrictSig (replicate arity topDmd) topRes
+ -- the call does not claim to be strict in its arguments, since they
+ -- may be lifted (foreign import prim) and the called code doen't
+ -- necessarily force them. See Trac #11076.
{-
************************************************************************
* *
diff --git a/testsuite/tests/stranal/should_run/T11076.hs b/testsuite/tests/stranal/should_run/T11076.hs
new file mode 100644
index 000000000000..f095cc1ff886
--- /dev/null
+++ b/testsuite/tests/stranal/should_run/T11076.hs
@@ -0,0 +1,15 @@
+{-
+ Test case for a problem where GHC had incorrect strictness
+ information for foreign calls with lifted arguments
+ -}
+{-# OPTIONS_GHC -O0 #-}
+module Main where
+
+import T11076A
+import Control.Exception
+x :: Bool
+x = error "OK: x has been forced"
+
+main :: IO ()
+main = print (testBool x) `catch`
+ \(ErrorCall e) -> putStrLn e -- x should be forced
diff --git a/testsuite/tests/stranal/should_run/T11076.stdout b/testsuite/tests/stranal/should_run/T11076.stdout
new file mode 100644
index 000000000000..8a17d8b29b6d
--- /dev/null
+++ b/testsuite/tests/stranal/should_run/T11076.stdout
@@ -0,0 +1 @@
+OK: x has been forced
diff --git a/testsuite/tests/stranal/should_run/T11076A.hs b/testsuite/tests/stranal/should_run/T11076A.hs
new file mode 100644
index 000000000000..153a887ef6c8
--- /dev/null
+++ b/testsuite/tests/stranal/should_run/T11076A.hs
@@ -0,0 +1,21 @@
+{-# OPTIONS_GHC -O #-}
+{-# LANGUAGE MagicHash,
+ ForeignFunctionInterface,
+ UnliftedFFITypes,
+ GHCForeignImportPrim,
+ BangPatterns
+ #-}
+module T11076A where
+
+import GHC.Exts
+import Unsafe.Coerce
+
+{-
+ If the demand type for the foreign call argument is incorrectly strict,
+ the bang pattern can be optimized out
+ -}
+testBool :: Bool -> Int
+testBool !x = I# (cmm_testPrim (unsafeCoerce x))
+{-# INLINE testBool #-}
+
+foreign import prim "testPrim" cmm_testPrim :: Any -> Int#
diff --git a/testsuite/tests/stranal/should_run/T11076_prim.cmm b/testsuite/tests/stranal/should_run/T11076_prim.cmm
new file mode 100644
index 000000000000..6e738a78a178
--- /dev/null
+++ b/testsuite/tests/stranal/should_run/T11076_prim.cmm
@@ -0,0 +1,10 @@
+#include "Cmm.h"
+#include "MachDeps.h"
+
+testPrim(gcptr x)
+{
+ W_ a;
+ a = 123;
+ return (a);
+}
+
diff --git a/testsuite/tests/stranal/should_run/all.T b/testsuite/tests/stranal/should_run/all.T
index 8a82ce86a5a1..efd1afaa353a 100644
--- a/testsuite/tests/stranal/should_run/all.T
+++ b/testsuite/tests/stranal/should_run/all.T
@@ -10,3 +10,4 @@ test('T7649', normal, compile_and_run, [''])
test('T9254', normal, compile_and_run, [''])
test('T10148', normal, compile_and_run, [''])
test('T10218', normal, compile_and_run, [''])
+test('T11076', normal, multimod_compile_and_run, ['T11076.hs', 'T11076_prim.cmm'])
diff --git a/testsuite/tests/stranal/sigs/T8598.stderr b/testsuite/tests/stranal/sigs/T8598.stderr
index 8de5d31a01db..a457cc5f507e 100644
--- a/testsuite/tests/stranal/sigs/T8598.stderr
+++ b/testsuite/tests/stranal/sigs/T8598.stderr
@@ -1,5 +1,5 @@
==================== Strictness signatures ====================
-T8598.fun: <S(S),1*U(U)>m
+T8598.fun: <S,1*U(U)>m
--
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