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[GlobalISel] Implement computeKnownBits for G_ASSERT_SEXT

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Implementation is the same as G_SEXT_INREG.

Differential Revision: https://reviews.llvm.org/D96899
This commit is contained in:
Jessica Paquette 2021-02-17 11:54:51 -08:00
parent 6cbf1f03bf
commit db301f643f
2 changed files with 72 additions and 0 deletions
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1
lib/CodeGen/GlobalISel/GISelKnownBits.cpp
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@ -347,6 +347,7 @@ void GISelKnownBits::computeKnownBitsImpl(Register R, KnownBits &Known,
Known = Known.sext(BitWidth);
break;
}
case TargetOpcode::G_ASSERT_SEXT:
case TargetOpcode::G_SEXT_INREG: {
computeKnownBitsImpl(MI.getOperand(1).getReg(), Known, DemandedElts,
Depth + 1);

71
unittests/CodeGen/GlobalISel/KnownBitsTest.cpp
View File

@ -842,6 +842,77 @@ TEST_F(AArch64GISelMITest, TestKnownBitsSextInReg) {
EXPECT_EQ(1u, Res.Zero.getZExtValue());
}
TEST_F(AArch64GISelMITest, TestKnownBitsAssertSext) {
StringRef MIRString = R"(
; 000...0001
%one:_(s32) = G_CONSTANT i32 1
; 000...0010
%two:_(s32) = G_CONSTANT i32 2
; 000...1010
%ten:_(s32) = G_CONSTANT i32 10
; ???...????
%w0:_(s32) = COPY $w0
; ???...?1?
%or:_(s32) = G_OR %w0, %two
; All bits are known.
%assert_sext1:_(s32) = G_ASSERT_SEXT %one, 1
%copy_assert_sext1:_(s32) = COPY %assert_sext1
; All bits unknown
%assert_sext2:_(s32) = G_ASSERT_SEXT %or, 1
%copy_assert_sext2:_(s32) = COPY %assert_sext2
; Extending from the only (known) set bit
; 111...11?
%assert_sext3:_(s32) = G_ASSERT_SEXT %or, 2
%copy_assert_sext3:_(s32) = COPY %assert_sext3
; Extending from a known set bit, overwriting all of the high set bits.
; 111...1110
%assert_sext4:_(s32) = G_ASSERT_SEXT %ten, 2
%copy_assert_sext4:_(s32) = COPY %assert_sext4
)";
setUp(MIRString);
if (!TM)
return;
GISelKnownBits Info(*MF);
KnownBits Res;
auto GetKB = [&](unsigned Idx) {
Register CopyReg = Copies[Idx];
auto *Copy = MRI->getVRegDef(CopyReg);
return Info.getKnownBits(Copy->getOperand(1).getReg());
};
// Every bit is known to be a 1.
Res = GetKB(Copies.size() - 4);
EXPECT_EQ(32u, Res.getBitWidth());
EXPECT_TRUE(Res.isAllOnes());
// All bits are unknown
Res = GetKB(Copies.size() - 3);
EXPECT_EQ(32u, Res.getBitWidth());
EXPECT_TRUE(Res.isUnknown());
// Extending from the only known set bit
// 111...11?
Res = GetKB(Copies.size() - 2);
EXPECT_EQ(32u, Res.getBitWidth());
EXPECT_EQ(0xFFFFFFFEu, Res.One.getZExtValue());
EXPECT_EQ(0u, Res.Zero.getZExtValue());
// Extending from a known set bit, overwriting all of the high set bits.
// 111...1110
Res = GetKB(Copies.size() - 1);
EXPECT_EQ(32u, Res.getBitWidth());
EXPECT_EQ(0xFFFFFFFEu, Res.One.getZExtValue());
EXPECT_EQ(1u, Res.Zero.getZExtValue());
}
TEST_F(AArch64GISelMITest, TestKnownBitsMergeValues) {
StringRef MIRString = R"(
%val0:_(s16) = G_CONSTANT i16 35224