Dynamically probe word size

run.sh

@@ -7,9 +7,16 @@ TEST_GHC="${TEST_GHC:-ghc}"
 CABAL="${CABAL:-cabal}"
 EMULATOR="${EMULATOR:-}"
 
+if "$TEST_GHC" --info | grep -q '("target word size","8")'; then
+    echo "Found 64-bit target"
+else
+    echo "Found 32-bit target"
+    CABAL_ARGS="-ftarget-32-bit"
+fi
+
 build_runit() {
     ALLOW_NEWER="--allow-newer=base"
-    "$CABAL" build $ALLOW_NEWER -w "$TEST_GHC" run-it
+    "$CABAL" build $ALLOW_NEWER -w "$TEST_GHC" $CABAL_ARGS run-it
     RUNIT="$("$CABAL" list-bin $ALLOW_NEWER -w "$TEST_GHC" run-it)"
     echo "runit is $RUNIT"
 }
@@ -23,7 +30,7 @@ run() {
     if [[ -n "$EMULATOR" ]]; then
         args+=( "--emulator=$EMULATOR" )
     fi
-    "$CABAL" run -w "$BOOT_GHC" test-primops -- "${args[@]}" "$@"
+    "$CABAL" run -w "$BOOT_GHC" $CABAL_ARGS test-primops -- "${args[@]}" "$@"
 }
 
 repl() {

src/RunGhc.hs

+{-# LANGUAGE CPP #-}
+
 -- | Utilities for running GHC and evaluating Cmm via @run-it@.
 module RunGhc
     ( EvalMethod(..)
@@ -95,8 +97,13 @@ mkStaticWrapper comp width = do
 hsType :: Width -> String
 hsType W8  = "Word8#"
 hsType W16 = "Word16#"
+#if defined(WORD_SIZE_32BIT)
+hsType W32 = "Word32#"
+hsType W64 = "Word64#"
+#else
 hsType W32 = "Word32#"
 hsType W64 = "Word#"
+#endif
 
 toHsWord :: Width -> String -> String
 toHsWord w x = "W# " <> parens (extendFn <> " " <> parens x)

src/Width.hs

@@ -30,9 +30,9 @@ import Data.Proxy
 import Test.QuickCheck hiding ((.&.))
 import Prelude hiding (truncate)
 
-#if WORD_SIZE_IN_BITS == 32
+#if defined(WORD_SIZE_32BIT)
 type WordSize = W32
-#elif WORD_SIZE_IN_BITS == 64
+#elif defined(WORD_SIZE_64BIT)
 type WordSize = W64
 #else
 #error unknown word size

test-primops.cabal

@@ -8,9 +8,19 @@ copyright:          (c) 2021 Ben Gamari
 synopsis:
   A QuickCheck testsuite for GHC's Cmm pipeline.
 
+flag target-32bit
+    description:     Set to True when the compiler-under-test targets a
+                     platform with 32-bit word-size.
+    default:         False
+    manual:          True
+
 executable test-primops
     main-is:          Main.hs
     hs-source-dirs:   src
+    if flag(target-32bit)
+        cpp-options:  -DWORD_SIZE_32BIT
+    else
+        cpp-options:  -DWORD_SIZE_64BIT
     other-modules:    Width,
                       Number,
                       Expr,