[llvm] 64b2676 - [InstCombine] fold ctlz/cttz-of-select with 1 or more constant arms
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Mon Jun 21 08:11:11 PDT 2021
Author: Sanjay Patel
Date: 2021-06-21T11:04:12-04:00
New Revision: 64b2676ca8290c7ff971c6f5b7a355b0ae7693de
URL: https://github.com/llvm/llvm-project/commit/64b2676ca8290c7ff971c6f5b7a355b0ae7693de
DIFF: https://github.com/llvm/llvm-project/commit/64b2676ca8290c7ff971c6f5b7a355b0ae7693de.diff
LOG: [InstCombine] fold ctlz/cttz-of-select with 1 or more constant arms
Building on:
4c44b02d87
...and adding handling for the extra operand in these intrinsics.
This pattern is discussed in:
https://llvm.org/PR50140
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
llvm/test/Transforms/InstCombine/intrinsic-select.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index c198863f4269..556550b7c22b 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1080,6 +1080,11 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {
case Intrinsic::ctlz:
if (auto *I = foldCttzCtlz(*II, *this))
return I;
+
+ // If the operand is a select with constant arm(s), try to hoist ctlz/cttz.
+ if (auto *Sel = dyn_cast<SelectInst>(II->getArgOperand(0)))
+ if (Instruction *R = FoldOpIntoSelect(*II, Sel))
+ return R;
break;
case Intrinsic::ctpop:
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 257931d2050e..67aca4e345ad 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -941,8 +941,14 @@ static Value *foldOperationIntoSelectOperand(Instruction &I, Value *SO,
if (auto *II = dyn_cast<IntrinsicInst>(&I)) {
assert(canConstantFoldCallTo(II, cast<Function>(II->getCalledOperand())) &&
"Expected constant-foldable intrinsic");
+ Intrinsic::ID IID = II->getIntrinsicID();
+ SmallVector<Value *, 2> Args = {SO};
- return Builder.CreateIntrinsic(II->getIntrinsicID(), I.getType(), SO);
+ // Propagate the zero-is-undef argument to the new instruction.
+ if (IID == Intrinsic::ctlz || IID == Intrinsic::cttz)
+ Args.push_back(II->getArgOperand(1));
+
+ return Builder.CreateIntrinsic(IID, I.getType(), Args);
}
assert(I.isBinaryOp() && "Unexpected opcode for select folding");
diff --git a/llvm/test/Transforms/InstCombine/intrinsic-select.ll b/llvm/test/Transforms/InstCombine/intrinsic-select.ll
index 1ee792ded641..92c5e3b38bd7 100644
--- a/llvm/test/Transforms/InstCombine/intrinsic-select.ll
+++ b/llvm/test/Transforms/InstCombine/intrinsic-select.ll
@@ -14,8 +14,7 @@ declare <3 x i7> @llvm.ctpop.v3i7(<3 x i7>)
define i32 @ctlz_sel_const_true_false(i1 %b) {
; CHECK-LABEL: @ctlz_sel_const_true_false(
-; CHECK-NEXT: [[S:%.*]] = select i1 [[B:%.*]], i32 5, i32 -7
-; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.ctlz.i32(i32 [[S]], i1 true), !range [[RNG0:![0-9]+]]
+; CHECK-NEXT: [[C:%.*]] = select i1 [[B:%.*]], i32 29, i32 0
; CHECK-NEXT: ret i32 [[C]]
;
%s = select i1 %b, i32 5, i32 -7
@@ -25,8 +24,8 @@ define i32 @ctlz_sel_const_true_false(i1 %b) {
define i32 @ctlz_sel_const_true(i1 %b, i32 %x) {
; CHECK-LABEL: @ctlz_sel_const_true(
-; CHECK-NEXT: [[S:%.*]] = select i1 [[B:%.*]], i32 5, i32 [[X:%.*]]
-; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.ctlz.i32(i32 [[S]], i1 false), !range [[RNG1:![0-9]+]]
+; CHECK-NEXT: [[TMP1:%.*]] = call i32 @llvm.ctlz.i32(i32 [[X:%.*]], i1 false), !range [[RNG0:![0-9]+]]
+; CHECK-NEXT: [[C:%.*]] = select i1 [[B:%.*]], i32 29, i32 [[TMP1]]
; CHECK-NEXT: ret i32 [[C]]
;
%s = select i1 %b, i32 5, i32 %x
@@ -36,8 +35,8 @@ define i32 @ctlz_sel_const_true(i1 %b, i32 %x) {
define <3 x i17> @ctlz_sel_const_false(<3 x i1> %b, <3 x i17> %x) {
; CHECK-LABEL: @ctlz_sel_const_false(
-; CHECK-NEXT: [[S:%.*]] = select <3 x i1> [[B:%.*]], <3 x i17> [[X:%.*]], <3 x i17> <i17 7, i17 -1, i17 0>
-; CHECK-NEXT: [[C:%.*]] = call <3 x i17> @llvm.ctlz.v3i17(<3 x i17> [[S]], i1 true)
+; CHECK-NEXT: [[TMP1:%.*]] = call <3 x i17> @llvm.ctlz.v3i17(<3 x i17> [[X:%.*]], i1 true)
+; CHECK-NEXT: [[C:%.*]] = select <3 x i1> [[B:%.*]], <3 x i17> [[TMP1]], <3 x i17> <i17 14, i17 0, i17 undef>
; CHECK-NEXT: ret <3 x i17> [[C]]
;
%s = select <3 x i1> %b, <3 x i17> %x, <3 x i17> <i17 7, i17 -1, i17 0>
@@ -49,7 +48,7 @@ define i32 @ctlz_sel_const_true_false_extra_use(i1 %b) {
; CHECK-LABEL: @ctlz_sel_const_true_false_extra_use(
; CHECK-NEXT: [[S:%.*]] = select i1 [[B:%.*]], i32 -1, i32 7
; CHECK-NEXT: call void @use(i32 [[S]])
-; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.ctlz.i32(i32 [[S]], i1 true), !range [[RNG2:![0-9]+]]
+; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.ctlz.i32(i32 [[S]], i1 true), !range [[RNG1:![0-9]+]]
; CHECK-NEXT: ret i32 [[C]]
;
%s = select i1 %b, i32 -1, i32 7
@@ -60,8 +59,7 @@ define i32 @ctlz_sel_const_true_false_extra_use(i1 %b) {
define i32 @cttz_sel_const_true_false(i1 %b) {
; CHECK-LABEL: @cttz_sel_const_true_false(
-; CHECK-NEXT: [[S:%.*]] = select i1 [[B:%.*]], i32 4, i32 -7
-; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 true), !range [[RNG1]]
+; CHECK-NEXT: [[C:%.*]] = select i1 [[B:%.*]], i32 2, i32 0
; CHECK-NEXT: ret i32 [[C]]
;
%s = select i1 %b, i32 4, i32 -7
@@ -71,8 +69,8 @@ define i32 @cttz_sel_const_true_false(i1 %b) {
define i32 @cttz_sel_const_true(i1 %b, i32 %x) {
; CHECK-LABEL: @cttz_sel_const_true(
-; CHECK-NEXT: [[S:%.*]] = select i1 [[B:%.*]], i32 5, i32 [[X:%.*]]
-; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 true), !range [[RNG1]]
+; CHECK-NEXT: [[TMP1:%.*]] = call i32 @llvm.cttz.i32(i32 [[X:%.*]], i1 true), !range [[RNG0]]
+; CHECK-NEXT: [[C:%.*]] = select i1 [[B:%.*]], i32 0, i32 [[TMP1]]
; CHECK-NEXT: ret i32 [[C]]
;
%s = select i1 %b, i32 5, i32 %x
@@ -82,8 +80,8 @@ define i32 @cttz_sel_const_true(i1 %b, i32 %x) {
define <3 x i5> @cttz_sel_const_false(<3 x i1> %b, <3 x i5> %x) {
; CHECK-LABEL: @cttz_sel_const_false(
-; CHECK-NEXT: [[S:%.*]] = select <3 x i1> [[B:%.*]], <3 x i5> [[X:%.*]], <3 x i5> <i5 7, i5 -1, i5 0>
-; CHECK-NEXT: [[C:%.*]] = call <3 x i5> @llvm.cttz.v3i5(<3 x i5> [[S]], i1 false)
+; CHECK-NEXT: [[TMP1:%.*]] = call <3 x i5> @llvm.cttz.v3i5(<3 x i5> [[X:%.*]], i1 false)
+; CHECK-NEXT: [[C:%.*]] = select <3 x i1> [[B:%.*]], <3 x i5> [[TMP1]], <3 x i5> <i5 0, i5 0, i5 5>
; CHECK-NEXT: ret <3 x i5> [[C]]
;
%s = select <3 x i1> %b, <3 x i5> %x, <3 x i5> <i5 7, i5 -1, i5 0>
@@ -95,7 +93,7 @@ define i32 @cttz_sel_const_true_false_extra_use(i1 %b) {
; CHECK-LABEL: @cttz_sel_const_true_false_extra_use(
; CHECK-NEXT: [[S:%.*]] = select i1 [[B:%.*]], i32 5, i32 -8
; CHECK-NEXT: call void @use(i32 [[S]])
-; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 true), !range [[RNG1]]
+; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.cttz.i32(i32 [[S]], i1 true), !range [[RNG0]]
; CHECK-NEXT: ret i32 [[C]]
;
%s = select i1 %b, i32 5, i32 -8
@@ -116,7 +114,7 @@ define i32 @ctpop_sel_const_true_false(i1 %b) {
define i32 @ctpop_sel_const_true(i1 %b, i32 %x) {
; CHECK-LABEL: @ctpop_sel_const_true(
-; CHECK-NEXT: [[TMP1:%.*]] = call i32 @llvm.ctpop.i32(i32 [[X:%.*]]), !range [[RNG1]]
+; CHECK-NEXT: [[TMP1:%.*]] = call i32 @llvm.ctpop.i32(i32 [[X:%.*]]), !range [[RNG0]]
; CHECK-NEXT: [[C:%.*]] = select i1 [[B:%.*]], i32 2, i32 [[TMP1]]
; CHECK-NEXT: ret i32 [[C]]
;
@@ -140,7 +138,7 @@ define i32 @ctpop_sel_const_true_false_extra_use(i1 %b) {
; CHECK-LABEL: @ctpop_sel_const_true_false_extra_use(
; CHECK-NEXT: [[S:%.*]] = select i1 [[B:%.*]], i32 5, i32 7
; CHECK-NEXT: call void @use(i32 [[S]])
-; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.ctpop.i32(i32 [[S]]), !range [[RNG3:![0-9]+]]
+; CHECK-NEXT: [[C:%.*]] = call i32 @llvm.ctpop.i32(i32 [[S]]), !range [[RNG2:![0-9]+]]
; CHECK-NEXT: ret i32 [[C]]
;
%s = select i1 %b, i32 5, i32 7
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