[Git][ghc/ghc][master] CmmToC: fix CmmRegOff for 64-bit register on a 32-bit target

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
d151546e by Cheng Shao at 2023-01-24T12:11:29-05:00
CmmToC: fix CmmRegOff for 64-bit register on a 32-bit target

We used to print the offset value to a platform word sized integer.
This is incorrect when the offset is negative (e.g. output of cmm
constant folding) and the register is 64-bit but on a 32-bit target,
and may lead to incorrect runtime result (e.g. #22607).

The fix is simple: just treat it as a proper MO_Add, with the correct
width info inferred from the register itself.

Metric Increase:
    T12707
    T13379
    T4801
    T5321FD
    T5321Fun

- - - - -


1 changed file:

- compiler/GHC/CmmToC.hs


Changes:

=====================================
compiler/GHC/CmmToC.hs
=====================================
@@ -382,8 +382,8 @@ pprExpr platform e = case e of
     CmmRegOff reg 0    -> pprCastReg reg
 
     -- CmmRegOff is an alias of MO_Add
-    CmmRegOff reg i -> pprCastReg reg <> char '+' <>
-                       pprHexVal platform (fromIntegral i) (wordWidth platform)
+    CmmRegOff reg i    -> pprExpr platform $ CmmMachOp (MO_Add w) [CmmReg reg, CmmLit $ CmmInt (toInteger i) w]
+      where w = cmmRegWidth platform reg
 
     CmmMachOp mop args -> pprMachOpApp platform mop args
 



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/d151546e59a50158f25c3df6728b00d3c27bb4b9

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/d151546e59a50158f25c3df6728b00d3c27bb4b9
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