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[InstCombine] Add support for simplifying ctlz/cttz intrinsics based on known bits.

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llvm-svn: 304669
This commit is contained in:
Craig Topper 2017-06-03 18:50:32 +00:00
parent e9a9480241
commit 076ba7a503
2 changed files with 5 additions and 15 deletions
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6
lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -1373,10 +1373,6 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombiner &IC) {
II.getIntrinsicID() == Intrinsic::ctlz) &&
"Expected cttz or ctlz intrinsic");
Value *Op0 = II.getArgOperand(0);
// FIXME: Try to simplify vectors of integers.
auto *IT = dyn_cast<IntegerType>(Op0->getType());
if (!IT)
return nullptr;
KnownBits Known = IC.computeKnownBits(Op0, 0, &II);
@ -1392,7 +1388,7 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombiner &IC) {
// FIXME: This should be in InstSimplify because we're replacing an
// instruction with a constant.
if (PossibleZeros == DefiniteZeros) {
auto *C = ConstantInt::get(IT, DefiniteZeros);
auto *C = ConstantInt::get(Op0->getType(), DefiniteZeros);
return IC.replaceInstUsesWith(II, C);
}

14
test/Transforms/InstCombine/intrinsics.ll
View File

@ -285,10 +285,7 @@ define i32 @cttz(i32 %a) {
define <2 x i32> @cttz_vec(<2 x i32> %a) {
; CHECK-LABEL: @cttz_vec(
; CHECK-NEXT: [[OR:%.*]] = or <2 x i32> [[A:%.*]], <i32 8, i32 8>
; CHECK-NEXT: [[AND:%.*]] = and <2 x i32> [[OR]], <i32 -8, i32 -8>
; CHECK-NEXT: [[COUNT:%.*]] = tail call <2 x i32> @llvm.cttz.v2i32(<2 x i32> [[AND]], i1 true)
; CHECK-NEXT: ret <2 x i32> [[COUNT]]
; CHECK-NEXT: ret <2 x i32> <i32 3, i32 3>
;
%or = or <2 x i32> %a, <i32 8, i32 8>
%and = and <2 x i32> %or, <i32 -8, i32 -8>
@ -382,10 +379,7 @@ define i8 @ctlz(i8 %a) {
define <2 x i8> @ctlz_vec(<2 x i8> %a) {
; CHECK-LABEL: @ctlz_vec(
; CHECK-NEXT: [[OR:%.*]] = or <2 x i8> [[A:%.*]], <i8 32, i8 32>
; CHECK-NEXT: [[AND:%.*]] = and <2 x i8> [[OR]], <i8 63, i8 63>
; CHECK-NEXT: [[COUNT:%.*]] = tail call <2 x i8> @llvm.ctlz.v2i8(<2 x i8> [[AND]], i1 true)
; CHECK-NEXT: ret <2 x i8> [[COUNT]]
; CHECK-NEXT: ret <2 x i8> <i8 2, i8 2>
;
%or = or <2 x i8> %a, <i8 32, i8 32>
%and = and <2 x i8> %or, <i8 63, i8 63>
@ -556,7 +550,7 @@ define i32 @ctlz_make_undef(i32 %a) {
define <2 x i32> @ctlz_make_undef_vec(<2 x i32> %a) {
; CHECK-LABEL: @ctlz_make_undef_vec(
; CHECK-NEXT: [[OR:%.*]] = or <2 x i32> [[A:%.*]], <i32 8, i32 8>
; CHECK-NEXT: [[CTLZ:%.*]] = tail call <2 x i32> @llvm.ctlz.v2i32(<2 x i32> [[OR]], i1 false)
; CHECK-NEXT: [[CTLZ:%.*]] = tail call <2 x i32> @llvm.ctlz.v2i32(<2 x i32> [[OR]], i1 true)
; CHECK-NEXT: ret <2 x i32> [[CTLZ]]
;
%or = or <2 x i32> %a, <i32 8, i32 8>
@ -593,7 +587,7 @@ define i32 @cttz_make_undef(i32 %a) {
define <2 x i32> @cttz_make_undef_vec(<2 x i32> %a) {
; CHECK-LABEL: @cttz_make_undef_vec(
; CHECK-NEXT: [[OR:%.*]] = or <2 x i32> [[A:%.*]], <i32 8, i32 8>
; CHECK-NEXT: [[CTTZ:%.*]] = tail call <2 x i32> @llvm.cttz.v2i32(<2 x i32> [[OR]], i1 false)
; CHECK-NEXT: [[CTTZ:%.*]] = tail call <2 x i32> @llvm.cttz.v2i32(<2 x i32> [[OR]], i1 true)
; CHECK-NEXT: ret <2 x i32> [[CTTZ]]
;
%or = or <2 x i32> %a, <i32 8, i32 8>