[PATCH] D116469: [AMDGPU][KnownBits] Correct the known bits calculation for MUL_I24.
Craig Topper via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Sun Jan 2 14:06:56 PST 2022
craig.topper updated this revision to Diff 396947.
craig.topper added a comment.
Remove KnownBits change
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D116469/new/
https://reviews.llvm.org/D116469
Files:
llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
Index: llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUISelLowering.cpp
@@ -4626,11 +4626,12 @@
RHSKnown = RHSKnown.trunc(24);
if (Opc == AMDGPUISD::MUL_I24) {
- unsigned LHSValBits = 24 - LHSKnown.countMinSignBits();
- unsigned RHSValBits = 24 - RHSKnown.countMinSignBits();
- unsigned MaxValBits = std::min(LHSValBits + RHSValBits, 32u);
- if (MaxValBits >= 32)
+ unsigned LHSValBits = 24 - LHSKnown.countMinSignBits() + 1;
+ unsigned RHSValBits = 24 - RHSKnown.countMinSignBits() + 1;
+ unsigned MaxValBits = LHSValBits + RHSValBits;
+ if (MaxValBits > 32)
break;
+ unsigned SignBits = 32 - MaxValBits + 1;
bool LHSNegative = LHSKnown.isNegative();
bool LHSNonNegative = LHSKnown.isNonNegative();
bool LHSPositive = LHSKnown.isStrictlyPositive();
@@ -4639,9 +4640,9 @@
bool RHSPositive = RHSKnown.isStrictlyPositive();
if ((LHSNonNegative && RHSNonNegative) || (LHSNegative && RHSNegative))
- Known.Zero.setHighBits(32 - MaxValBits);
+ Known.Zero.setHighBits(SignBits);
else if ((LHSNegative && RHSPositive) || (LHSPositive && RHSNegative))
- Known.One.setHighBits(32 - MaxValBits);
+ Known.One.setHighBits(SignBits);
} else {
unsigned LHSValBits = 24 - LHSKnown.countMinLeadingZeros();
unsigned RHSValBits = 24 - RHSKnown.countMinLeadingZeros();
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