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[GISel] Correct the known bits of G_ANYEXT 

Known bits for G_ANYEXT was incorrectly using KnownBits::zext, causing
us to treat the high bits as zero even though they're (by definition)
unknown.

Differential Revision: https://reviews.llvm.org/D86323
This commit is contained in:
Justin Bogner 2020-08-20 17:03:18 -07:00
parent 70923983e5
commit 1283dca007
2 changed files with 45 additions and 1 deletions
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2
llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
View File

@ -316,7 +316,7 @@ void GISelKnownBits::computeKnownBitsImpl(Register R, KnownBits &Known,
case TargetOpcode::G_ANYEXT: {
computeKnownBitsImpl(MI.getOperand(1).getReg(), Known, DemandedElts,
Depth + 1);
Known = Known.zext(BitWidth);
Known = Known.anyext(BitWidth);
break;
}
case TargetOpcode::G_LOAD: {

44
llvm/unittests/CodeGen/GlobalISel/KnownBitsTest.cpp
View File

@ -511,3 +511,47 @@ TEST_F(AArch64GISelMITest, TestMetadata) {
Mask.flipAllBits();
EXPECT_EQ(Mask.getZExtValue(), Res.Zero.getZExtValue());
}
TEST_F(AArch64GISelMITest, TestKnownBitsExt) {
StringRef MIRString = " %c1:_(s16) = G_CONSTANT i16 1\n"
" %x:_(s16) = G_IMPLICIT_DEF\n"
" %y:_(s16) = G_AND %x, %c1\n"
" %anyext:_(s32) = G_ANYEXT %y(s16)\n"
" %r1:_(s32) = COPY %anyext\n"
" %zext:_(s32) = G_ZEXT %y(s16)\n"
" %r2:_(s32) = COPY %zext\n"
" %sext:_(s32) = G_SEXT %y(s16)\n"
" %r3:_(s32) = COPY %sext\n";
setUp(MIRString);
if (!TM)
return;
Register CopyRegAny = Copies[Copies.size() - 3];
Register CopyRegZ = Copies[Copies.size() - 2];
Register CopyRegS = Copies[Copies.size() - 1];
GISelKnownBits Info(*MF);
MachineInstr *Copy;
Register SrcReg;
KnownBits Res;
Copy = MRI->getVRegDef(CopyRegAny);
SrcReg = Copy->getOperand(1).getReg();
Res = Info.getKnownBits(SrcReg);
EXPECT_EQ((uint64_t)32, Res.getBitWidth());
EXPECT_EQ((uint64_t)0, Res.One.getZExtValue());
EXPECT_EQ((uint64_t)0x0000fffe, Res.Zero.getZExtValue());
Copy = MRI->getVRegDef(CopyRegZ);
SrcReg = Copy->getOperand(1).getReg();
Res = Info.getKnownBits(SrcReg);
EXPECT_EQ((uint64_t)32, Res.getBitWidth());
EXPECT_EQ((uint64_t)0, Res.One.getZExtValue());
EXPECT_EQ((uint64_t)0xfffffffe, Res.Zero.getZExtValue());
Copy = MRI->getVRegDef(CopyRegS);
SrcReg = Copy->getOperand(1).getReg();
Res = Info.getKnownBits(SrcReg);
EXPECT_EQ((uint64_t)32, Res.getBitWidth());
EXPECT_EQ((uint64_t)0, Res.One.getZExtValue());
EXPECT_EQ((uint64_t)0xfffffffe, Res.Zero.getZExtValue());
}