[llvm] r179317 - Fix undefined behavior in AArch64
David Majnemer
david.majnemer at gmail.com
Thu Apr 11 13:13:52 PDT 2013
Author: majnemer
Date: Thu Apr 11 15:13:52 2013
New Revision: 179317
URL: http://llvm.org/viewvc/llvm-project?rev=179317&view=rev
Log:
Fix undefined behavior in AArch64
A64Imms::isLogicalImmBits and A64Imms::isLogicalImm will attempt to
execute shifts that perform undefined behavior. Instead of attempting
to perform the 64-bit rotation, treat it as a no-op.
Modified:
llvm/trunk/lib/Target/AArch64/Utils/AArch64BaseInfo.cpp
Modified: llvm/trunk/lib/Target/AArch64/Utils/AArch64BaseInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/Utils/AArch64BaseInfo.cpp?rev=179317&r1=179316&r2=179317&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/Utils/AArch64BaseInfo.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/Utils/AArch64BaseInfo.cpp Thu Apr 11 15:13:52 2013
@@ -981,8 +981,11 @@ bool A64Imms::isLogicalImm(unsigned RegW
Rotation = RepeatWidth - Rotation;
}
- uint64_t ReplicatedOnes = (ReplicatedMask >> Rotation)
- | ((ReplicatedMask << (RepeatWidth - Rotation)) & RepeatMask);
+ uint64_t ReplicatedOnes = ReplicatedMask;
+ if (Rotation != 0 && Rotation != 64)
+ ReplicatedOnes = (ReplicatedMask >> Rotation)
+ | ((ReplicatedMask << (RepeatWidth - Rotation)) & RepeatMask);
+
// Of course, they may not actually be ones, so we have to check that:
if (!isMask_64(ReplicatedOnes))
continue;
@@ -1051,13 +1054,14 @@ bool A64Imms::isLogicalImmBits(unsigned
int Rotation = (ImmR & (Width - 1));
uint64_t Mask = (1ULL << Num1s) - 1;
uint64_t WidthMask = Width == 64 ? -1 : (1ULL << Width) - 1;
- Mask = (Mask >> Rotation)
- | ((Mask << (Width - Rotation)) & WidthMask);
+ if (Rotation != 0 && Rotation != 64)
+ Mask = (Mask >> Rotation)
+ | ((Mask << (Width - Rotation)) & WidthMask);
- Imm = 0;
- for (unsigned i = 0; i < RegWidth / Width; ++i) {
- Imm |= Mask;
+ Imm = Mask;
+ for (unsigned i = 1; i < RegWidth / Width; ++i) {
Mask <<= Width;
+ Imm |= Mask;
}
return true;
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