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Differential D28780

[ValueTracking] Extend known bits to understand @llvm.bitreverse.
ClosedPublic

Authored by mcrosier on Jan 16 2017, 2:27 PM.

Details

Reviewers
regehr
spatel
RKSimon
reames
Commits
rG8520429bdde0: [ValueTracking] Extend known bits to understand @llvm.bitreverse.
rL292233: [ValueTracking] Extend known bits to understand @llvm.bitreverse.
Summary

I saw r292130 in passing and figured we should add the same support in value tracking.

Chad

Diff Detail

Event Timeline

mcrosier created this revision.Jan 16 2017, 2:27 PM
RKSimon accepted this revision.Jan 17 2017, 3:57 AM

LGTM - vector tests would be nice but many don't currently work with instcombine

This revision is now accepted and ready to land.Jan 17 2017, 3:57 AM
Closed by commit rL292233: [ValueTracking] Extend known bits to understand @llvm.bitreverse. (authored by mcrosier). · Explain WhyJan 17 2017, 9:34 AM
This revision was automatically updated to reflect the committed changes.

Revision Contents

PathSize
lib/
Analysis/
5 lines
test/
Transforms/
InstCombine/
34 lines
InstSimplify/
31 lines

Diff 84596

lib/Analysis/ValueTracking.cpp

Show First 20 Lines • Show All 1,394 Lines • ▼ Show 20 Lines case Instruction::Invoke:
if (const Value *RV = ImmutableCallSite(I).getReturnedArgOperand()) { if (const Value *RV = ImmutableCallSite(I).getReturnedArgOperand()) {
computeKnownBits(RV, KnownZero2, KnownOne2, Depth + 1, Q); computeKnownBits(RV, KnownZero2, KnownOne2, Depth + 1, Q);
KnownZero |= KnownZero2; KnownZero |= KnownZero2;
KnownOne |= KnownOne2; KnownOne |= KnownOne2;
} }
if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
switch (II->getIntrinsicID()) { switch (II->getIntrinsicID()) {
default: break; default: break;
case Intrinsic::bitreverse:
computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, Depth + 1, Q);
KnownZero = KnownZero2.reverseBits();
KnownOne = KnownOne2.reverseBits();
break;
case Intrinsic::bswap: case Intrinsic::bswap:
computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, Depth + 1, Q); computeKnownBits(I->getOperand(0), KnownZero2, KnownOne2, Depth + 1, Q);
KnownZero |= KnownZero2.byteSwap(); KnownZero |= KnownZero2.byteSwap();
KnownOne |= KnownOne2.byteSwap(); KnownOne |= KnownOne2.byteSwap();
break; break;
case Intrinsic::ctlz: case Intrinsic::ctlz:
case Intrinsic::cttz: { case Intrinsic::cttz: {
unsigned LowBits = Log2_32(BitWidth)+1; unsigned LowBits = Log2_32(BitWidth)+1;
▲ Show 20 Lines • Show All 2,996 Lines • Show Last 20 Lines

test/Transforms/InstCombine/bitreverse-known-bits.ll

  • This file was added.
; RUN: opt < %s -S -instcombine | FileCheck %s
declare i32 @llvm.bitreverse.i32(i32)
; CHECK-LABEL: @test1
; CHECK: ret i1 true
define i1 @test1(i32 %arg) {
%a = or i32 %arg, 4294901760
%b = call i32 @llvm.bitreverse.i32(i32 %a)
%and = and i32 %b, 65535
%res = icmp eq i32 %and, 65535
ret i1 %res
}
; CHECK-LABEL: @test2
; CHECK: ret i1 true
define i1 @test2(i32 %arg) {
%a = or i32 %arg, 1
%b = call i32 @llvm.bitreverse.i32(i32 %a)
%c = and i32 %b, 2147483648
%d = call i32 @llvm.bitreverse.i32(i32 %c)
%res = icmp eq i32 %d, 1
ret i1 %res
}
; CHECK-LABEL: @test3
; CHECK: ret i1 false
define i1 @test3(i32 %arg) {
%a = or i32 %arg, 65536
%b = call i32 @llvm.bitreverse.i32(i32 %a)
%and = and i32 %b, 32768
%res = icmp eq i32 %and, 0
ret i1 %res
}

test/Transforms/InstSimplify/bitreverse.ll

  • This file was added.
; RUN: opt < %s -S -instsimplify | FileCheck %s
declare i32 @llvm.bitreverse.i32(i32)
; CHECK-LABEL: @test1(
; CHECK: ret i1 false
define i1 @test1(i32 %arg) {
%a = or i32 %arg, 1
%b = call i32 @llvm.bitreverse.i32(i32 %a)
%res = icmp eq i32 %b, 0
ret i1 %res
}
; CHECK-LABEL: @test2(
; CHECK: ret i1 false
define i1 @test2(i32 %arg) {
%a = or i32 %arg, 1024
%b = call i32 @llvm.bitreverse.i32(i32 %a)
%res = icmp eq i32 %b, 0
ret i1 %res
}
; CHECK-LABEL: @test3(
; CHECK: ret i1 false
define i1 @test3(i32 %arg) {
%a = and i32 %arg, 1
%b = call i32 @llvm.bitreverse.i32(i32 %a)
%and = and i32 %b, 1
%res = icmp eq i32 %and, 1
ret i1 %res
}