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llvm-project/llvm/unittests/Analysis/ValueTrackingTest.cpp
Sanjay Patel cac28b452e [ValueTracking] peek through 2-input shuffles in ComputeNumSignBits 
This patch gives the IR ComputeNumSignBits the same functionality as the 
DAG version (the code is derived from the existing code).

This an extension of the single input shuffle analysis added with D53659.

Differential Revision: https://reviews.llvm.org/D53987

llvm-svn: 346071
2018-11-03 13:18:55 +00:00

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19 KiB
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//===- ValueTrackingTest.cpp - ValueTracking tests ------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/AsmParser/Parser.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/InstIterator.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/KnownBits.h"
#include "gtest/gtest.h"
using namespace llvm;
namespace {
class MatchSelectPatternTest : public testing::Test {
protected:
void parseAssembly(const char *Assembly) {
SMDiagnostic Error;
M = parseAssemblyString(Assembly, Error, Context);
std::string errMsg;
raw_string_ostream os(errMsg);
Error.print("", os);
// A failure here means that the test itself is buggy.
if (!M)
report_fatal_error(os.str());
Function *F = M->getFunction("test");
if (F == nullptr)
report_fatal_error("Test must have a function named @test");
A = nullptr;
for (inst_iterator I = inst_begin(F), E = inst_end(F); I != E; ++I) {
if (I->hasName()) {
if (I->getName() == "A")
A = &*I;
}
}
if (A == nullptr)
report_fatal_error("@test must have an instruction %A");
}
void expectPattern(const SelectPatternResult &P) {
Value *LHS, *RHS;
Instruction::CastOps CastOp;
SelectPatternResult R = matchSelectPattern(A, LHS, RHS, &CastOp);
EXPECT_EQ(P.Flavor, R.Flavor);
EXPECT_EQ(P.NaNBehavior, R.NaNBehavior);
EXPECT_EQ(P.Ordered, R.Ordered);
}
LLVMContext Context;
std::unique_ptr<Module> M;
Instruction *A, *B;
};
}
TEST_F(MatchSelectPatternTest, SimpleFMin) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ult float %a, 5.0\n"
" %A = select i1 %1, float %a, float 5.0\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMINNUM, SPNB_RETURNS_NAN, false});
}
TEST_F(MatchSelectPatternTest, SimpleFMax) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float %a, 5.0\n"
" %A = select i1 %1, float %a, float 5.0\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMAXNUM, SPNB_RETURNS_OTHER, true});
}
TEST_F(MatchSelectPatternTest, SwappedFMax) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float 5.0, %a\n"
" %A = select i1 %1, float %a, float 5.0\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMAXNUM, SPNB_RETURNS_OTHER, false});
}
TEST_F(MatchSelectPatternTest, SwappedFMax2) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float %a, 5.0\n"
" %A = select i1 %1, float 5.0, float %a\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMAXNUM, SPNB_RETURNS_NAN, false});
}
TEST_F(MatchSelectPatternTest, SwappedFMax3) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ult float %a, 5.0\n"
" %A = select i1 %1, float 5.0, float %a\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMAXNUM, SPNB_RETURNS_OTHER, true});
}
TEST_F(MatchSelectPatternTest, FastFMin) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp nnan olt float %a, 5.0\n"
" %A = select i1 %1, float %a, float 5.0\n"
" ret float %A\n"
"}\n");
expectPattern({SPF_FMINNUM, SPNB_RETURNS_ANY, false});
}
TEST_F(MatchSelectPatternTest, FMinConstantZero) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ole float %a, 0.0\n"
" %A = select i1 %1, float %a, float 0.0\n"
" ret float %A\n"
"}\n");
// This shouldn't be matched, as %a could be -0.0.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMinConstantZeroNsz) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp nsz ole float %a, 0.0\n"
" %A = select i1 %1, float %a, float 0.0\n"
" ret float %A\n"
"}\n");
// But this should be, because we've ignored signed zeroes.
expectPattern({SPF_FMINNUM, SPNB_RETURNS_OTHER, true});
}
TEST_F(MatchSelectPatternTest, FMinMismatchConstantZero1) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float -0.0, %a\n"
" %A = select i1 %1, float 0.0, float %a\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMinMismatchConstantZero2) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float %a, -0.0\n"
" %A = select i1 %1, float 0.0, float %a\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMinMismatchConstantZero3) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float 0.0, %a\n"
" %A = select i1 %1, float -0.0, float %a\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMinMismatchConstantZero4) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float %a, 0.0\n"
" %A = select i1 %1, float -0.0, float %a\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMinMismatchConstantZero5) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float -0.0, %a\n"
" %A = select i1 %1, float %a, float 0.0\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMinMismatchConstantZero6) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float %a, -0.0\n"
" %A = select i1 %1, float %a, float 0.0\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMinMismatchConstantZero7) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float 0.0, %a\n"
" %A = select i1 %1, float %a, float -0.0\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMinMismatchConstantZero8) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float %a, 0.0\n"
" %A = select i1 %1, float %a, float -0.0\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMaxMismatchConstantZero1) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float -0.0, %a\n"
" %A = select i1 %1, float 0.0, float %a\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMaxMismatchConstantZero2) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float %a, -0.0\n"
" %A = select i1 %1, float 0.0, float %a\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMaxMismatchConstantZero3) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float 0.0, %a\n"
" %A = select i1 %1, float -0.0, float %a\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMaxMismatchConstantZero4) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float %a, 0.0\n"
" %A = select i1 %1, float -0.0, float %a\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMaxMismatchConstantZero5) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float -0.0, %a\n"
" %A = select i1 %1, float %a, float 0.0\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMaxMismatchConstantZero6) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float %a, -0.0\n"
" %A = select i1 %1, float %a, float 0.0\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMaxMismatchConstantZero7) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp olt float 0.0, %a\n"
" %A = select i1 %1, float %a, float -0.0\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, FMaxMismatchConstantZero8) {
parseAssembly(
"define float @test(float %a) {\n"
" %1 = fcmp ogt float %a, 0.0\n"
" %A = select i1 %1, float %a, float -0.0\n"
" ret float %A\n"
"}\n");
// FIXME: The sign of zero doesn't matter in fcmp.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, VectorFMinimum) {
parseAssembly(
"define <4 x float> @test(<4 x float> %a) {\n"
" %1 = fcmp ule <4 x float> %a, \n"
" <float 5.0, float 5.0, float 5.0, float 5.0>\n"
" %A = select <4 x i1> %1, <4 x float> %a,\n"
" <4 x float> <float 5.0, float 5.0, float 5.0, float 5.0>\n"
" ret <4 x float> %A\n"
"}\n");
// Check that pattern matching works on vectors where each lane has the same
// unordered pattern.
expectPattern({SPF_FMINNUM, SPNB_RETURNS_NAN, false});
}
TEST_F(MatchSelectPatternTest, VectorFMinOtherOrdered) {
parseAssembly(
"define <4 x float> @test(<4 x float> %a) {\n"
" %1 = fcmp ole <4 x float> %a, \n"
" <float 5.0, float 5.0, float 5.0, float 5.0>\n"
" %A = select <4 x i1> %1, <4 x float> %a,\n"
" <4 x float> <float 5.0, float 5.0, float 5.0, float 5.0>\n"
" ret <4 x float> %A\n"
"}\n");
// Check that pattern matching works on vectors where each lane has the same
// ordered pattern.
expectPattern({SPF_FMINNUM, SPNB_RETURNS_OTHER, true});
}
TEST_F(MatchSelectPatternTest, VectorNotFMinimum) {
parseAssembly(
"define <4 x float> @test(<4 x float> %a) {\n"
" %1 = fcmp ule <4 x float> %a, \n"
" <float 5.0, float 0x7ff8000000000000, float 5.0, float 5.0>\n"
" %A = select <4 x i1> %1, <4 x float> %a,\n"
" <4 x float> <float 5.0, float 0x7ff8000000000000, float 5.0, float "
"5.0>\n"
" ret <4 x float> %A\n"
"}\n");
// The lane that contains a NaN (0x7ff80...) behaves like a
// non-NaN-propagating min and the other lines behave like a NaN-propagating
// min, so check that neither is returned.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, VectorNotFMinZero) {
parseAssembly(
"define <4 x float> @test(<4 x float> %a) {\n"
" %1 = fcmp ule <4 x float> %a, \n"
" <float 5.0, float -0.0, float 5.0, float 5.0>\n"
" %A = select <4 x i1> %1, <4 x float> %a,\n"
" <4 x float> <float 5.0, float 0.0, float 5.0, float 5.0>\n"
" ret <4 x float> %A\n"
"}\n");
// Always selects the second lane of %a if it is positive or negative zero, so
// this is stricter than a min.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, DoubleCastU) {
parseAssembly(
"define i32 @test(i8 %a, i8 %b) {\n"
" %1 = icmp ult i8 %a, %b\n"
" %2 = zext i8 %a to i32\n"
" %3 = zext i8 %b to i32\n"
" %A = select i1 %1, i32 %2, i32 %3\n"
" ret i32 %A\n"
"}\n");
// We should be able to look through the situation where we cast both operands
// to the select.
expectPattern({SPF_UMIN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, DoubleCastS) {
parseAssembly(
"define i32 @test(i8 %a, i8 %b) {\n"
" %1 = icmp slt i8 %a, %b\n"
" %2 = sext i8 %a to i32\n"
" %3 = sext i8 %b to i32\n"
" %A = select i1 %1, i32 %2, i32 %3\n"
" ret i32 %A\n"
"}\n");
// We should be able to look through the situation where we cast both operands
// to the select.
expectPattern({SPF_SMIN, SPNB_NA, false});
}
TEST_F(MatchSelectPatternTest, DoubleCastBad) {
parseAssembly(
"define i32 @test(i8 %a, i8 %b) {\n"
" %1 = icmp ult i8 %a, %b\n"
" %2 = zext i8 %a to i32\n"
" %3 = sext i8 %b to i32\n"
" %A = select i1 %1, i32 %2, i32 %3\n"
" ret i32 %A\n"
"}\n");
// The cast types here aren't the same, so we cannot match an UMIN.
expectPattern({SPF_UNKNOWN, SPNB_NA, false});
}
TEST(ValueTracking, GuaranteedToTransferExecutionToSuccessor) {
StringRef Assembly =
"declare void @nounwind_readonly(i32*) nounwind readonly "
"declare void @nounwind_argmemonly(i32*) nounwind argmemonly "
"declare void @throws_but_readonly(i32*) readonly "
"declare void @throws_but_argmemonly(i32*) argmemonly "
" "
"declare void @unknown(i32*) "
" "
"define void @f(i32* %p) { "
" call void @nounwind_readonly(i32* %p) "
" call void @nounwind_argmemonly(i32* %p) "
" call void @throws_but_readonly(i32* %p) "
" call void @throws_but_argmemonly(i32* %p) "
" call void @unknown(i32* %p) nounwind readonly "
" call void @unknown(i32* %p) nounwind argmemonly "
" call void @unknown(i32* %p) readonly "
" call void @unknown(i32* %p) argmemonly "
" ret void "
"} ";
LLVMContext Context;
SMDiagnostic Error;
auto M = parseAssemblyString(Assembly, Error, Context);
assert(M && "Bad assembly?");
auto *F = M->getFunction("f");
assert(F && "Bad assembly?");
auto &BB = F->getEntryBlock();
bool ExpectedAnswers[] = {
true, // call void @nounwind_readonly(i32* %p)
true, // call void @nounwind_argmemonly(i32* %p)
false, // call void @throws_but_readonly(i32* %p)
false, // call void @throws_but_argmemonly(i32* %p)
true, // call void @unknown(i32* %p) nounwind readonly
true, // call void @unknown(i32* %p) nounwind argmemonly
false, // call void @unknown(i32* %p) readonly
false, // call void @unknown(i32* %p) argmemonly
false, // ret void
};
int Index = 0;
for (auto &I : BB) {
EXPECT_EQ(isGuaranteedToTransferExecutionToSuccessor(&I),
ExpectedAnswers[Index])
<< "Incorrect answer at instruction " << Index << " = " << I;
Index++;
}
}
TEST(ValueTracking, ComputeNumSignBits_PR32045) {
StringRef Assembly = "define i32 @f(i32 %a) { "
" %val = ashr i32 %a, -1 "
" ret i32 %val "
"} ";
LLVMContext Context;
SMDiagnostic Error;
auto M = parseAssemblyString(Assembly, Error, Context);
assert(M && "Bad assembly?");
auto *F = M->getFunction("f");
assert(F && "Bad assembly?");
auto *RVal =
cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
EXPECT_EQ(ComputeNumSignBits(RVal, M->getDataLayout()), 1u);
}
// No guarantees for canonical IR in this analysis, so this just bails out.
TEST(ValueTracking, ComputeNumSignBits_Shuffle) {
StringRef Assembly = "define <2 x i32> @f() { "
" %val = shufflevector <2 x i32> undef, <2 x i32> undef, <2 x i32> <i32 0, i32 0> "
" ret <2 x i32> %val "
"} ";
LLVMContext Context;
SMDiagnostic Error;
auto M = parseAssemblyString(Assembly, Error, Context);
assert(M && "Bad assembly?");
auto *F = M->getFunction("f");
assert(F && "Bad assembly?");
auto *RVal =
cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
EXPECT_EQ(ComputeNumSignBits(RVal, M->getDataLayout()), 1u);
}
// No guarantees for canonical IR in this analysis, so a shuffle element that
// references an undef value means this can't return any extra information.
TEST(ValueTracking, ComputeNumSignBits_Shuffle2) {
StringRef Assembly = "define <2 x i32> @f(<2 x i1> %x) { "
" %sext = sext <2 x i1> %x to <2 x i32> "
" %val = shufflevector <2 x i32> %sext, <2 x i32> undef, <2 x i32> <i32 0, i32 2> "
" ret <2 x i32> %val "
"} ";
LLVMContext Context;
SMDiagnostic Error;
auto M = parseAssemblyString(Assembly, Error, Context);
assert(M && "Bad assembly?");
auto *F = M->getFunction("f");
assert(F && "Bad assembly?");
auto *RVal =
cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
EXPECT_EQ(ComputeNumSignBits(RVal, M->getDataLayout()), 1u);
}
TEST(ValueTracking, ComputeKnownBits) {
StringRef Assembly = "define i32 @f(i32 %a, i32 %b) { "
" %ash = mul i32 %a, 8 "
" %aad = add i32 %ash, 7 "
" %aan = and i32 %aad, 4095 "
" %bsh = shl i32 %b, 4 "
" %bad = or i32 %bsh, 6 "
" %ban = and i32 %bad, 4095 "
" %mul = mul i32 %aan, %ban "
" ret i32 %mul "
"} ";
LLVMContext Context;
SMDiagnostic Error;
auto M = parseAssemblyString(Assembly, Error, Context);
assert(M && "Bad assembly?");
auto *F = M->getFunction("f");
assert(F && "Bad assembly?");
auto *RVal =
cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
auto Known = computeKnownBits(RVal, M->getDataLayout());
ASSERT_FALSE(Known.hasConflict());
EXPECT_EQ(Known.One.getZExtValue(), 10u);
EXPECT_EQ(Known.Zero.getZExtValue(), 4278190085u);
}
TEST(ValueTracking, ComputeKnownMulBits) {
StringRef Assembly = "define i32 @f(i32 %a, i32 %b) { "
" %aa = shl i32 %a, 5 "
" %bb = shl i32 %b, 5 "
" %aaa = or i32 %aa, 24 "
" %bbb = or i32 %bb, 28 "
" %mul = mul i32 %aaa, %bbb "
" ret i32 %mul "
"} ";
LLVMContext Context;
SMDiagnostic Error;
auto M = parseAssemblyString(Assembly, Error, Context);
assert(M && "Bad assembly?");
auto *F = M->getFunction("f");
assert(F && "Bad assembly?");
auto *RVal =
cast<ReturnInst>(F->getEntryBlock().getTerminator())->getOperand(0);
auto Known = computeKnownBits(RVal, M->getDataLayout());
ASSERT_FALSE(Known.hasConflict());
EXPECT_EQ(Known.One.getZExtValue(), 32u);
EXPECT_EQ(Known.Zero.getZExtValue(), 95u);
}
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