[llvm] [InstCombine] fold `select (trunc nuw X to i1), X, Y` to `select (trunc nuw X to i1), 1, Y` (PR #105914)
via llvm-commits
llvm-commits at lists.llvm.org
Sat Aug 24 01:02:01 PDT 2024
https://github.com/c8ef updated https://github.com/llvm/llvm-project/pull/105914
>From 5b7752afa5aec5299e986ab9bca26007fbaea810 Mon Sep 17 00:00:00 2001
From: c8ef <c8ef at outlook.com>
Date: Sat, 24 Aug 2024 09:47:29 +0800
Subject: [PATCH 1/3] fold select (trunc nuw X to i1), X, Y
---
.../InstCombine/InstCombineSelect.cpp | 10 ++++++
.../InstCombine/fold-select-trunc-if-nuw.ll | 35 +++++++++++++++++++
2 files changed, 45 insertions(+)
create mode 100644 llvm/test/Transforms/InstCombine/fold-select-trunc-if-nuw.ll
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 18ffc209f259e0..49582004d9a4f6 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -4201,5 +4201,15 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
}
}
+ // select (trunc nuw X to i1), X, Y --> select (trunc nuw X to i1), 1, Y
+ if (auto *TI = dyn_cast<TruncInst>(CondVal)) {
+ Value *Trunc;
+ if (TI->hasNoUnsignedWrap() && match(CondVal, m_Trunc(m_Value(Trunc))) &&
+ match(TrueVal, m_Specific(Trunc))) {
+ return SelectInst::Create(
+ CondVal, ConstantInt::get(TrueVal->getType(), 1), FalseVal);
+ }
+ }
+
return nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/fold-select-trunc-if-nuw.ll b/llvm/test/Transforms/InstCombine/fold-select-trunc-if-nuw.ll
new file mode 100644
index 00000000000000..09fb2d77f9ef56
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/fold-select-trunc-if-nuw.ll
@@ -0,0 +1,35 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i8 @fold_select_trunc_if_nuw(i8 %x, i8 %y) {
+; CHECK-LABEL: @fold_select_trunc_if_nuw(
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc nuw i8 [[X:%.*]] to i1
+; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 1, i8 [[Y:%.*]]
+; CHECK-NEXT: ret i8 [[RET]]
+;
+ %trunc = trunc nuw i8 %x to i1
+ %ret = select i1 %trunc, i8 %x, i8 %y
+ ret i8 %ret
+}
+
+define i8 @fold_select_trunc_if_nuw_negative(i8 %x, i8 %y) {
+; CHECK-LABEL: @fold_select_trunc_if_nuw_negative(
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc nsw i8 [[X:%.*]] to i1
+; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 [[X]], i8 [[Y:%.*]]
+; CHECK-NEXT: ret i8 [[RET]]
+;
+ %trunc = trunc nsw i8 %x to i1
+ %ret = select i1 %trunc, i8 %x, i8 %y
+ ret i8 %ret
+}
+
+define <2 x i8> @fold_select_trunc_if_nuw_vector(<2 x i8> %x, <2 x i8> %y) {
+; CHECK-LABEL: @fold_select_trunc_if_nuw_vector(
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc nuw <2 x i8> [[X:%.*]] to <2 x i1>
+; CHECK-NEXT: [[RET:%.*]] = select <2 x i1> [[TRUNC]], <2 x i8> <i8 1, i8 1>, <2 x i8> [[Y:%.*]]
+; CHECK-NEXT: ret <2 x i8> [[RET]]
+;
+ %trunc = trunc nuw <2 x i8> %x to <2 x i1>
+ %ret = select <2 x i1> %trunc, <2 x i8> %x, <2 x i8> %y
+ ret <2 x i8> %ret
+}
>From 5b9e6c717ebf53c5ea5e13cbf900d5c257aa9e53 Mon Sep 17 00:00:00 2001
From: c8ef <c8ef at outlook.com>
Date: Sat, 24 Aug 2024 15:48:43 +0800
Subject: [PATCH 2/3] add more fold; use replaceOperand; rewrite test
---
.../InstCombine/InstCombineSelect.cpp | 22 ++++--
.../InstCombine/fold-select-trunc-if-nuw.ll | 35 ----------
.../InstCombine/fold-select-trunc.ll | 68 +++++++++++++++++++
3 files changed, 83 insertions(+), 42 deletions(-)
delete mode 100644 llvm/test/Transforms/InstCombine/fold-select-trunc-if-nuw.ll
create mode 100644 llvm/test/Transforms/InstCombine/fold-select-trunc.ll
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 49582004d9a4f6..16903800d9dafd 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -4202,13 +4202,21 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
}
// select (trunc nuw X to i1), X, Y --> select (trunc nuw X to i1), 1, Y
- if (auto *TI = dyn_cast<TruncInst>(CondVal)) {
- Value *Trunc;
- if (TI->hasNoUnsignedWrap() && match(CondVal, m_Trunc(m_Value(Trunc))) &&
- match(TrueVal, m_Specific(Trunc))) {
- return SelectInst::Create(
- CondVal, ConstantInt::get(TrueVal->getType(), 1), FalseVal);
- }
+ // select (trunc nuw X to i1), Y, X --> select (trunc nuw X to i1), Y, 0
+ // select (trunc nsw X to i1), X, Y --> select (trunc nsw X to i1), -1, Y
+ // select (trunc nsw X to i1), Y, X --> select (trunc nsw X to i1), Y, 0
+ Value *Trunc;
+ if (match(CondVal, m_NUWTrunc(m_Value(Trunc)))) {
+ if (match(TrueVal, m_Specific(Trunc)))
+ return replaceOperand(SI, 1, ConstantInt::get(TrueVal->getType(), 1));
+ if (match(FalseVal, m_Specific(Trunc)))
+ return replaceOperand(SI, 2, ConstantInt::get(TrueVal->getType(), 0));
+ }
+ if (match(CondVal, m_NSWTrunc(m_Value(Trunc)))) {
+ if (match(TrueVal, m_Specific(Trunc)))
+ return replaceOperand(SI, 1, ConstantInt::get(TrueVal->getType(), -1));
+ if (match(FalseVal, m_Specific(Trunc)))
+ return replaceOperand(SI, 2, ConstantInt::get(TrueVal->getType(), 0));
}
return nullptr;
diff --git a/llvm/test/Transforms/InstCombine/fold-select-trunc-if-nuw.ll b/llvm/test/Transforms/InstCombine/fold-select-trunc-if-nuw.ll
deleted file mode 100644
index 09fb2d77f9ef56..00000000000000
--- a/llvm/test/Transforms/InstCombine/fold-select-trunc-if-nuw.ll
+++ /dev/null
@@ -1,35 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -passes=instcombine -S | FileCheck %s
-
-define i8 @fold_select_trunc_if_nuw(i8 %x, i8 %y) {
-; CHECK-LABEL: @fold_select_trunc_if_nuw(
-; CHECK-NEXT: [[TRUNC:%.*]] = trunc nuw i8 [[X:%.*]] to i1
-; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 1, i8 [[Y:%.*]]
-; CHECK-NEXT: ret i8 [[RET]]
-;
- %trunc = trunc nuw i8 %x to i1
- %ret = select i1 %trunc, i8 %x, i8 %y
- ret i8 %ret
-}
-
-define i8 @fold_select_trunc_if_nuw_negative(i8 %x, i8 %y) {
-; CHECK-LABEL: @fold_select_trunc_if_nuw_negative(
-; CHECK-NEXT: [[TRUNC:%.*]] = trunc nsw i8 [[X:%.*]] to i1
-; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 [[X]], i8 [[Y:%.*]]
-; CHECK-NEXT: ret i8 [[RET]]
-;
- %trunc = trunc nsw i8 %x to i1
- %ret = select i1 %trunc, i8 %x, i8 %y
- ret i8 %ret
-}
-
-define <2 x i8> @fold_select_trunc_if_nuw_vector(<2 x i8> %x, <2 x i8> %y) {
-; CHECK-LABEL: @fold_select_trunc_if_nuw_vector(
-; CHECK-NEXT: [[TRUNC:%.*]] = trunc nuw <2 x i8> [[X:%.*]] to <2 x i1>
-; CHECK-NEXT: [[RET:%.*]] = select <2 x i1> [[TRUNC]], <2 x i8> <i8 1, i8 1>, <2 x i8> [[Y:%.*]]
-; CHECK-NEXT: ret <2 x i8> [[RET]]
-;
- %trunc = trunc nuw <2 x i8> %x to <2 x i1>
- %ret = select <2 x i1> %trunc, <2 x i8> %x, <2 x i8> %y
- ret <2 x i8> %ret
-}
diff --git a/llvm/test/Transforms/InstCombine/fold-select-trunc.ll b/llvm/test/Transforms/InstCombine/fold-select-trunc.ll
new file mode 100644
index 00000000000000..9bc0a5a2bd8fc8
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/fold-select-trunc.ll
@@ -0,0 +1,68 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i8 @fold_select_trunc_nuw_true(i8 %x, i8 %y) {
+; CHECK-LABEL: @fold_select_trunc_nuw_true(
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc nuw i8 [[X:%.*]] to i1
+; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 1, i8 [[Y:%.*]]
+; CHECK-NEXT: ret i8 [[RET]]
+;
+ %trunc = trunc nuw i8 %x to i1
+ %ret = select i1 %trunc, i8 %x, i8 %y
+ ret i8 %ret
+}
+
+define i8 @fold_select_trunc_nuw_false(i8 %x, i8 %y) {
+; CHECK-LABEL: @fold_select_trunc_nuw_false(
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc nuw i8 [[X:%.*]] to i1
+; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 [[Y:%.*]], i8 0
+; CHECK-NEXT: ret i8 [[RET]]
+;
+ %trunc = trunc nuw i8 %x to i1
+ %ret = select i1 %trunc, i8 %y, i8 %x
+ ret i8 %ret
+}
+
+define i8 @fold_select_trunc_nsw_true(i8 %x, i8 %y) {
+; CHECK-LABEL: @fold_select_trunc_nsw_true(
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc nsw i8 [[X:%.*]] to i1
+; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 -1, i8 [[Y:%.*]]
+; CHECK-NEXT: ret i8 [[RET]]
+;
+ %trunc = trunc nsw i8 %x to i1
+ %ret = select i1 %trunc, i8 %x, i8 %y
+ ret i8 %ret
+}
+
+define i8 @fold_select_trunc_nsw_false(i8 %x, i8 %y) {
+; CHECK-LABEL: @fold_select_trunc_nsw_false(
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc nsw i8 [[X:%.*]] to i1
+; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 [[Y:%.*]], i8 0
+; CHECK-NEXT: ret i8 [[RET]]
+;
+ %trunc = trunc nsw i8 %x to i1
+ %ret = select i1 %trunc, i8 %y, i8 %x
+ ret i8 %ret
+}
+
+define i8 @fold_select_trunc_negative(i8 %x, i8 %y) {
+; CHECK-LABEL: @fold_select_trunc_negative(
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc i8 [[X:%.*]] to i1
+; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 [[X]], i8 [[Y:%.*]]
+; CHECK-NEXT: ret i8 [[RET]]
+;
+ %trunc = trunc i8 %x to i1
+ %ret = select i1 %trunc, i8 %x, i8 %y
+ ret i8 %ret
+}
+
+define <2 x i8> @fold_select_trunc_vector(<2 x i8> %x, <2 x i8> %y) {
+; CHECK-LABEL: @fold_select_trunc_vector(
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc nuw <2 x i8> [[X:%.*]] to <2 x i1>
+; CHECK-NEXT: [[RET:%.*]] = select <2 x i1> [[TRUNC]], <2 x i8> <i8 1, i8 1>, <2 x i8> [[Y:%.*]]
+; CHECK-NEXT: ret <2 x i8> [[RET]]
+;
+ %trunc = trunc nuw <2 x i8> %x to <2 x i1>
+ %ret = select <2 x i1> %trunc, <2 x i8> %x, <2 x i8> %y
+ ret <2 x i8> %ret
+}
>From def908da230baeda971b4b1e36eb65b9160d1e2e Mon Sep 17 00:00:00 2001
From: c8ef <c8ef at outlook.com>
Date: Sat, 24 Aug 2024 16:01:47 +0800
Subject: [PATCH 3/3] add i128 test
---
.../Transforms/InstCombine/InstCombineSelect.cpp | 15 ++++++++-------
.../Transforms/InstCombine/fold-select-trunc.ll | 14 +++++++-------
2 files changed, 15 insertions(+), 14 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 16903800d9dafd..fcd11126073bf1 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -4207,16 +4207,17 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
// select (trunc nsw X to i1), Y, X --> select (trunc nsw X to i1), Y, 0
Value *Trunc;
if (match(CondVal, m_NUWTrunc(m_Value(Trunc)))) {
- if (match(TrueVal, m_Specific(Trunc)))
+ if (TrueVal == Trunc)
return replaceOperand(SI, 1, ConstantInt::get(TrueVal->getType(), 1));
- if (match(FalseVal, m_Specific(Trunc)))
- return replaceOperand(SI, 2, ConstantInt::get(TrueVal->getType(), 0));
+ if (FalseVal == Trunc)
+ return replaceOperand(SI, 2, ConstantInt::get(FalseVal->getType(), 0));
}
if (match(CondVal, m_NSWTrunc(m_Value(Trunc)))) {
- if (match(TrueVal, m_Specific(Trunc)))
- return replaceOperand(SI, 1, ConstantInt::get(TrueVal->getType(), -1));
- if (match(FalseVal, m_Specific(Trunc)))
- return replaceOperand(SI, 2, ConstantInt::get(TrueVal->getType(), 0));
+ if (TrueVal == Trunc)
+ return replaceOperand(SI, 1,
+ Constant::getAllOnesValue(TrueVal->getType()));
+ if (FalseVal == Trunc)
+ return replaceOperand(SI, 2, ConstantInt::get(FalseVal->getType(), 0));
}
return nullptr;
diff --git a/llvm/test/Transforms/InstCombine/fold-select-trunc.ll b/llvm/test/Transforms/InstCombine/fold-select-trunc.ll
index 9bc0a5a2bd8fc8..5567d7d5e1fca9 100644
--- a/llvm/test/Transforms/InstCombine/fold-select-trunc.ll
+++ b/llvm/test/Transforms/InstCombine/fold-select-trunc.ll
@@ -23,15 +23,15 @@ define i8 @fold_select_trunc_nuw_false(i8 %x, i8 %y) {
ret i8 %ret
}
-define i8 @fold_select_trunc_nsw_true(i8 %x, i8 %y) {
+define i128 @fold_select_trunc_nsw_true(i128 %x, i128 %y) {
; CHECK-LABEL: @fold_select_trunc_nsw_true(
-; CHECK-NEXT: [[TRUNC:%.*]] = trunc nsw i8 [[X:%.*]] to i1
-; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i8 -1, i8 [[Y:%.*]]
-; CHECK-NEXT: ret i8 [[RET]]
+; CHECK-NEXT: [[TRUNC:%.*]] = trunc nsw i128 [[X:%.*]] to i1
+; CHECK-NEXT: [[RET:%.*]] = select i1 [[TRUNC]], i128 -1, i128 [[Y:%.*]]
+; CHECK-NEXT: ret i128 [[RET]]
;
- %trunc = trunc nsw i8 %x to i1
- %ret = select i1 %trunc, i8 %x, i8 %y
- ret i8 %ret
+ %trunc = trunc nsw i128 %x to i1
+ %ret = select i1 %trunc, i128 %x, i128 %y
+ ret i128 %ret
}
define i8 @fold_select_trunc_nsw_false(i8 %x, i8 %y) {
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