[llvm] 27b651c - [InstCombine] cttz(zext(x)) -> zext(cttz(x)) if the 'ZeroIsUndef' parameter is 'true' (PR50172)
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Thu Jun 3 03:01:24 PDT 2021
Hi Dávid,
One of our internal tests that attempts to verify the intrinsic functions started to fail after your commit. I have put the details in PR50569, can you please take a look?
Douglas Yung
-----Original Message-----
From: llvm-commits <llvm-commits-bounces at lists.llvm.org> On Behalf Of Dávid Bolvanský via llvm-commits
Sent: Monday, May 3, 2021 8:05
To: llvm-commits at lists.llvm.org
Subject: [llvm] 27b651c - [InstCombine] cttz(zext(x)) -> zext(cttz(x)) if the 'ZeroIsUndef' parameter is 'true' (PR50172)
Author: Dávid Bolvanský
Date: 2021-05-03T17:05:12+02:00
New Revision: 27b651ca473ba33999888cc302efb5f856ec7cea
URL: https://github.com/llvm/llvm-project/commit/27b651ca473ba33999888cc302efb5f856ec7cea
DIFF: https://github.com/llvm/llvm-project/commit/27b651ca473ba33999888cc302efb5f856ec7cea.diff
LOG: [InstCombine] cttz(zext(x)) -> zext(cttz(x)) if the 'ZeroIsUndef' parameter is 'true' (PR50172)
Zext doesn't change the number of trailing zeros, so narrow cttz(zext(x)) -> zext(cttz(x)) if the 'ZeroIsUndef' parameter is 'true'.
Proofs:
https://alive2.llvm.org/ce/z/o2dnjY
Solves https://bugs.llvm.org/show_bug.cgi?id=50172
Reviewed By: spatel
Differential Revision: https://reviews.llvm.org/D101582
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
llvm/test/Transforms/InstCombine/cttz.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 345290aac384..15740bb410e6 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -424,6 +424,7 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombinerImpl &IC) {
"Expected cttz or ctlz intrinsic");
bool IsTZ = II.getIntrinsicID() == Intrinsic::cttz;
Value *Op0 = II.getArgOperand(0);
+ Value *Op1 = II.getArgOperand(1);
Value *X;
// ctlz(bitreverse(x)) -> cttz(x)
// cttz(bitreverse(x)) -> ctlz(x)
@@ -438,6 +439,15 @@ static Instruction *foldCttzCtlz(IntrinsicInst &II, InstCombinerImpl &IC) {
if (match(Op0, m_Neg(m_Value(X))))
return IC.replaceOperand(II, 0, X);
+ // Zext doesn't change the number of trailing zeros, so narrow:
+ // cttz(zext(x)) -> zext(cttz(x)) if the 'ZeroIsUndef' parameter is 'true'.
+ if (match(Op0, m_OneUse(m_ZExt(m_Value(X)))) && match(Op1, m_One())) {
+ auto *Cttz = IC.Builder.CreateBinaryIntrinsic(Intrinsic::cttz, X,
+ IC.Builder.getTrue());
+ auto *ZextCttz = IC.Builder.CreateZExt(Cttz, II.getType());
+ return IC.replaceInstUsesWith(II, ZextCttz);
+ }
+
// cttz(abs(x)) -> cttz(x)
// cttz(nabs(x)) -> cttz(x)
Value *Y;
diff --git a/llvm/test/Transforms/InstCombine/cttz.ll b/llvm/test/Transforms/InstCombine/cttz.ll
index 5babb1346ce3..8d50c68da37b 100644
--- a/llvm/test/Transforms/InstCombine/cttz.ll
+++ b/llvm/test/Transforms/InstCombine/cttz.ll
@@ -7,9 +7,9 @@ declare void @use(i32)
define i32 @cttz_zext_zero_undef(i16 %x) { ; CHECK-LABEL: @cttz_zext_zero_undef(
-; CHECK-NEXT: [[Z:%.*]] = zext i16 [[X:%.*]] to i32
-; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[Z]], i1 true), !range [[RNG0:![0-9]+]]
-; CHECK-NEXT: ret i32 [[TZ]]
+; CHECK-NEXT: [[TMP1:%.*]] = call i16 @llvm.cttz.i16(i16 [[X:%.*]], i1 true), !range [[RNG0:![0-9]+]]
+; CHECK-NEXT: [[TMP2:%.*]] = zext i16 [[TMP1]] to i32
+; CHECK-NEXT: ret i32 [[TMP2]]
;
%z = zext i16 %x to i32
%tz = call i32 @llvm.cttz.i32(i32 %z, i1 true) @@ -19,7 +19,7 @@ define i32 @cttz_zext_zero_undef(i16 %x) { define i32 @cttz_zext_zero_def(i16 %x) { ; CHECK-LABEL: @cttz_zext_zero_def(
; CHECK-NEXT: [[Z:%.*]] = zext i16 [[X:%.*]] to i32
-; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[Z]], i1 false), !range [[RNG0]]
+; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[Z]], i1 false), !range [[RNG1:![0-9]+]]
; CHECK-NEXT: ret i32 [[TZ]]
;
%z = zext i16 %x to i32
@@ -31,7 +31,7 @@ define i32 @cttz_zext_zero_undef_extra_use(i16 %x) { ; CHECK-LABEL: @cttz_zext_zero_undef_extra_use(
; CHECK-NEXT: [[Z:%.*]] = zext i16 [[X:%.*]] to i32
; CHECK-NEXT: call void @use(i32 [[Z]])
-; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[Z]], i1 true), !range [[RNG0]]
+; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[Z]], i1 true), !range [[RNG1]]
; CHECK-NEXT: ret i32 [[TZ]]
;
%z = zext i16 %x to i32
@@ -42,9 +42,9 @@ define i32 @cttz_zext_zero_undef_extra_use(i16 %x) {
define <2 x i64> @cttz_zext_zero_undef_vec(<2 x i32> %x) { ; CHECK-LABEL: @cttz_zext_zero_undef_vec(
-; CHECK-NEXT: [[Z:%.*]] = zext <2 x i32> [[X:%.*]] to <2 x i64>
-; CHECK-NEXT: [[TZ:%.*]] = tail call <2 x i64> @llvm.cttz.v2i64(<2 x i64> [[Z]], i1 true)
-; CHECK-NEXT: ret <2 x i64> [[TZ]]
+; CHECK-NEXT: [[TMP1:%.*]] = call <2 x i32> @llvm.cttz.v2i32(<2 x i32> [[X:%.*]], i1 true)
+; CHECK-NEXT: [[TMP2:%.*]] = zext <2 x i32> [[TMP1]] to <2 x i64>
+; CHECK-NEXT: ret <2 x i64> [[TMP2]]
;
%z = zext <2 x i32> %x to <2 x i64>
%tz = tail call <2 x i64> @llvm.cttz.v2i64(<2 x i64> %z, i1 true) @@ -65,7 +65,7 @@ define <2 x i64> @cttz_zext_zero_def_vec(<2 x i32> %x) { define i32 @cttz_sext_zero_undef(i16 %x) { ; CHECK-LABEL: @cttz_sext_zero_undef(
; CHECK-NEXT: [[S:%.*]] = sext i16 [[X:%.*]] to i32
-; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 true), !range [[RNG0]]
+; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 true), !range [[RNG1]]
; CHECK-NEXT: ret i32 [[TZ]]
;
%s = sext i16 %x to i32
@@ -76,7 +76,7 @@ define i32 @cttz_sext_zero_undef(i16 %x) { define i32 @cttz_sext_zero_def(i16 %x) { ; CHECK-LABEL: @cttz_sext_zero_def(
; CHECK-NEXT: [[S:%.*]] = zext i16 [[X:%.*]] to i32
-; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 false), !range [[RNG0]]
+; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 false), !range [[RNG1]]
; CHECK-NEXT: ret i32 [[TZ]]
;
%s = zext i16 %x to i32
@@ -84,11 +84,11 @@ define i32 @cttz_sext_zero_def(i16 %x) {
ret i32 %tz
}
-define i32 @cttz_zext_sero_undef_extra_use(i16 %x) { -; CHECK-LABEL: @cttz_zext_sero_undef_extra_use(
+define i32 @cttz_sext_zero_undef_extra_use(i16 %x) { ; CHECK-LABEL:
+ at cttz_sext_zero_undef_extra_use(
; CHECK-NEXT: [[S:%.*]] = sext i16 [[X:%.*]] to i32
; CHECK-NEXT: call void @use(i32 [[S]])
-; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 true), !range [[RNG0]]
+; CHECK-NEXT: [[TZ:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 true), !range [[RNG1]]
; CHECK-NEXT: ret i32 [[TZ]]
;
%s = sext i16 %x to i32
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