[llvm] [InstCombine] fold Select with a predicate consists of icmp connected by And (PR #76363)
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llvm-commits at lists.llvm.org
Mon Dec 25 08:26:07 PST 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
@llvm/pr-subscribers-llvm-analysis
Author: Chia (sun-jacobi)
<details>
<summary>Changes</summary>
This patch closes #<!-- -->76043.
---
We extended the pre-exist `foldSelectWithBinaryOp`, to make it support the below case:
```
%A = icmp eq %TV, %FV
%C = and %A, %B
%D = select %C, %TV, %FV
->
%FV
```
or
```
%A = icmp ne %TV, %FV
%C = or %A, %B
%D = select %C, %FV, %TV
->
%TV
```
The Alive2 proof: https://alive2.llvm.org/ce/z/XLyhE-
---
For updated test cases in `select-and-cmp.ll` and `select-or-cmp.ll`, we also provided Alive2 proof: https://alive2.llvm.org/ce/z/krhtZy
---
Full diff: https://github.com/llvm/llvm-project/pull/76363.diff
3 Files Affected:
- (modified) llvm/lib/Analysis/InstructionSimplify.cpp (+46-27)
- (modified) llvm/test/Transforms/InstSimplify/select-and-cmp.ll (+27-24)
- (modified) llvm/test/Transforms/InstSimplify/select-or-cmp.ll (+28-36)
``````````diff
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index 5beac5547d65e0..ca2fc9ca173c9a 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -79,15 +79,56 @@ static Value *simplifyInstructionWithOperands(Instruction *I,
const SimplifyQuery &SQ,
unsigned MaxRecurse);
+static Value *simplifySelectWithAndOR(Value *Cond, Value *TrueVal,
+ Value *FalseVal,
+ CmpInst::Predicate ExpectedPred,
+ BinaryOperator::BinaryOps BinOpCode,
+ unsigned int MaxRecurse) {
+ assert(
+ (BinOpCode == BinaryOperator::And || BinOpCode == BinaryOperator::Or) &&
+ "Binary Operator should be And or Or");
+
+ assert(
+ (BinOpCode == BinaryOperator::And && ExpectedPred == ICmpInst::ICMP_EQ) ||
+ (BinOpCode == BinaryOperator::Or && ExpectedPred == ICmpInst::ICMP_NE));
+
+ if (!MaxRecurse)
+ return nullptr;
+
+ auto getSimplifiedValue = [](BinaryOperator::BinaryOps BinOpCode,
+ Value *TrueVal, Value *FalseVal) {
+ return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal;
+ };
+
+ CmpInst::Predicate Pred;
+ if (match(Cond, m_c_ICmp(Pred, m_Specific(TrueVal), m_Specific(FalseVal))) &&
+ Pred == ExpectedPred)
+ return getSimplifiedValue(BinOpCode, TrueVal, FalseVal);
+
+ Value *X, *Y;
+ if (match(Cond, m_c_BinOp(BinOpCode, m_Value(X), m_Value(Y)))) {
+
+ auto matchBinOpCode = [&](Value *V) {
+ return simplifySelectWithAndOR(V, TrueVal, FalseVal, ExpectedPred,
+ BinOpCode, MaxRecurse - 1);
+ };
+
+ if (matchBinOpCode(X) || matchBinOpCode(Y))
+ return getSimplifiedValue(BinOpCode, TrueVal, FalseVal);
+ }
+
+ return nullptr;
+}
+
static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal,
- Value *FalseVal) {
+ Value *FalseVal, unsigned int MaxRecurse) {
BinaryOperator::BinaryOps BinOpCode;
if (auto *BO = dyn_cast<BinaryOperator>(Cond))
BinOpCode = BO->getOpcode();
else
return nullptr;
- CmpInst::Predicate ExpectedPred, Pred1, Pred2;
+ CmpInst::Predicate ExpectedPred;
if (BinOpCode == BinaryOperator::Or) {
ExpectedPred = ICmpInst::ICMP_NE;
} else if (BinOpCode == BinaryOperator::And) {
@@ -95,30 +136,8 @@ static Value *foldSelectWithBinaryOp(Value *Cond, Value *TrueVal,
} else
return nullptr;
- // %A = icmp eq %TV, %FV
- // %B = icmp eq %X, %Y (and one of these is a select operand)
- // %C = and %A, %B
- // %D = select %C, %TV, %FV
- // -->
- // %FV
-
- // %A = icmp ne %TV, %FV
- // %B = icmp ne %X, %Y (and one of these is a select operand)
- // %C = or %A, %B
- // %D = select %C, %TV, %FV
- // -->
- // %TV
- Value *X, *Y;
- if (!match(Cond, m_c_BinOp(m_c_ICmp(Pred1, m_Specific(TrueVal),
- m_Specific(FalseVal)),
- m_ICmp(Pred2, m_Value(X), m_Value(Y)))) ||
- Pred1 != Pred2 || Pred1 != ExpectedPred)
- return nullptr;
-
- if (X == TrueVal || X == FalseVal || Y == TrueVal || Y == FalseVal)
- return BinOpCode == BinaryOperator::Or ? TrueVal : FalseVal;
-
- return nullptr;
+ return simplifySelectWithAndOR(Cond, TrueVal, FalseVal, ExpectedPred,
+ BinOpCode, MaxRecurse);
}
/// For a boolean type or a vector of boolean type, return false or a vector
@@ -4906,7 +4925,7 @@ static Value *simplifySelectInst(Value *Cond, Value *TrueVal, Value *FalseVal,
if (Value *V = simplifySelectWithFCmp(Cond, TrueVal, FalseVal, Q))
return V;
- if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal))
+ if (Value *V = foldSelectWithBinaryOp(Cond, TrueVal, FalseVal, MaxRecurse))
return V;
std::optional<bool> Imp = isImpliedByDomCondition(Cond, Q.CxtI, Q.DL);
diff --git a/llvm/test/Transforms/InstSimplify/select-and-cmp.ll b/llvm/test/Transforms/InstSimplify/select-and-cmp.ll
index 41a4ab96bd62cc..8a48618e217084 100644
--- a/llvm/test/Transforms/InstSimplify/select-and-cmp.ll
+++ b/llvm/test/Transforms/InstSimplify/select-and-cmp.ll
@@ -78,6 +78,28 @@ define i32 @select_and_inv_icmp_alt(i32 %x, i32 %y, i32 %z) {
ret i32 %D
}
+define i32 @select_and_icmp_ne(i32 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @select_and_icmp_ne(
+; CHECK-NEXT: ret i32 [[X:%.*]]
+;
+ %A = icmp eq i32 %x, %z
+ %B = icmp ne i32 %y, %z
+ %C = and i1 %A, %B
+ %D = select i1 %C, i32 %z, i32 %x
+ ret i32 %D
+}
+
+define i32 @select_and_icmp_ne_alt(i32 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @select_and_icmp_ne_alt(
+; CHECK-NEXT: ret i32 [[Z:%.*]]
+;
+ %A = icmp eq i32 %x, %z
+ %B = icmp ne i32 %y, %z
+ %C = and i1 %A, %B
+ %D = select i1 %C, i32 %x, i32 %z
+ ret i32 %D
+}
+
define i32 @select_and_inv_icmp(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_and_inv_icmp(
; CHECK-NEXT: ret i32 [[X:%.*]]
@@ -115,21 +137,6 @@ define i32 @select_and_icmp_inv(i32 %x, i32 %y, i32 %z) {
; Negative tests
define i32 @select_and_icmp_pred_bad_1(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_and_icmp_pred_bad_1(
-; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT: [[B:%.*]] = icmp ne i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT: [[C:%.*]] = and i1 [[A]], [[B]]
-; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[X]]
-; CHECK-NEXT: ret i32 [[D]]
-;
- %A = icmp eq i32 %x, %z
- %B = icmp ne i32 %y, %z
- %C = and i1 %A, %B
- %D = select i1 %C, i32 %z, i32 %x
- ret i32 %D
-}
-
-define i32 @select_and_icmp_pred_bad_2(i32 %x, i32 %y, i32 %z) {
-; CHECK-LABEL: @select_and_icmp_pred_bad_2(
; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = icmp eq i32 [[Y:%.*]], [[Z]]
; CHECK-NEXT: [[C:%.*]] = and i1 [[A]], [[B]]
@@ -143,8 +150,8 @@ define i32 @select_and_icmp_pred_bad_2(i32 %x, i32 %y, i32 %z) {
ret i32 %D
}
-define i32 @select_and_icmp_pred_bad_3(i32 %x, i32 %y, i32 %z) {
-; CHECK-LABEL: @select_and_icmp_pred_bad_3(
+define i32 @select_and_icmp_pred_bad_2(i32 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @select_and_icmp_pred_bad_2(
; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = icmp ne i32 [[Y:%.*]], [[Z]]
; CHECK-NEXT: [[C:%.*]] = and i1 [[A]], [[B]]
@@ -158,8 +165,8 @@ define i32 @select_and_icmp_pred_bad_3(i32 %x, i32 %y, i32 %z) {
ret i32 %D
}
-define i32 @select_and_icmp_pred_bad_4(i32 %x, i32 %y, i32 %z) {
-; CHECK-LABEL: @select_and_icmp_pred_bad_4(
+define i32 @select_and_icmp_pred_bad_3(i32 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @select_and_icmp_pred_bad_3(
; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = icmp eq i32 [[Y:%.*]], [[Z]]
; CHECK-NEXT: [[C:%.*]] = or i1 [[A]], [[B]]
@@ -235,11 +242,7 @@ define i32 @select_and_icmp_bad_op_2(i32 %x, i32 %y, i32 %z, i32 %k) {
define i32 @select_and_icmp_alt_bad_1(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_and_icmp_alt_bad_1(
-; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT: [[B:%.*]] = icmp ne i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT: [[C:%.*]] = and i1 [[A]], [[B]]
-; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[X]], i32 [[Z]]
-; CHECK-NEXT: ret i32 [[D]]
+; CHECK-NEXT: ret i32 [[Z:%.*]]
;
%A = icmp eq i32 %x, %z
%B = icmp ne i32 %y, %z
diff --git a/llvm/test/Transforms/InstSimplify/select-or-cmp.ll b/llvm/test/Transforms/InstSimplify/select-or-cmp.ll
index 0e410a9645f0d2..8b91ea03062695 100644
--- a/llvm/test/Transforms/InstSimplify/select-or-cmp.ll
+++ b/llvm/test/Transforms/InstSimplify/select-or-cmp.ll
@@ -78,6 +78,28 @@ define i32 @select_or_inv_icmp_alt(i32 %x, i32 %y, i32 %z) {
ret i32 %D
}
+define i32 @select_or_icmp_eq(i32 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @select_or_icmp_eq(
+; CHECK-NEXT: ret i32 [[X:%.*]]
+;
+ %A = icmp ne i32 %x, %z
+ %B = icmp eq i32 %y, %z
+ %C = or i1 %A, %B
+ %D = select i1 %C, i32 %x, i32 %z
+ ret i32 %D
+}
+
+define i32 @select_or_icmp_eq_alt(i32 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @select_or_icmp_eq_alt(
+; CHECK-NEXT: ret i32 [[Z:%.*]]
+;
+ %A = icmp ne i32 %x, %z
+ %B = icmp eq i32 %y, %z
+ %C = or i1 %A, %B
+ %D = select i1 %C, i32 %z, i32 %x
+ ret i32 %D
+}
+
define <2 x i8> @select_or_icmp_alt_vec(<2 x i8> %x, <2 x i8> %y, <2 x i8> %z) {
; CHECK-LABEL: @select_or_icmp_alt_vec(
; CHECK-NEXT: ret <2 x i8> [[X:%.*]]
@@ -129,21 +151,6 @@ define i32 @select_and_icmp_pred_bad_1(i32 %x, i32 %y, i32 %z) {
define i32 @select_and_icmp_pred_bad_2(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_and_icmp_pred_bad_2(
-; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT: [[B:%.*]] = icmp eq i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT: [[C:%.*]] = or i1 [[A]], [[B]]
-; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[Z]], i32 [[X]]
-; CHECK-NEXT: ret i32 [[D]]
-;
- %A = icmp ne i32 %x, %z
- %B = icmp eq i32 %y, %z
- %C = or i1 %A, %B
- %D = select i1 %C, i32 %z, i32 %x
- ret i32 %D
-}
-
-define i32 @select_and_icmp_pred_bad_3(i32 %x, i32 %y, i32 %z) {
-; CHECK-LABEL: @select_and_icmp_pred_bad_3(
; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = icmp eq i32 [[Y:%.*]], [[Z]]
; CHECK-NEXT: [[C:%.*]] = or i1 [[A]], [[B]]
@@ -157,8 +164,8 @@ define i32 @select_and_icmp_pred_bad_3(i32 %x, i32 %y, i32 %z) {
ret i32 %D
}
-define i32 @select_and_icmp_pred_bad_4(i32 %x, i32 %y, i32 %z) {
-; CHECK-LABEL: @select_and_icmp_pred_bad_4(
+define i32 @select_and_icmp_pred_bad_3(i32 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @select_and_icmp_pred_bad_3(
; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = icmp ne i32 [[Y:%.*]], [[Z]]
; CHECK-NEXT: [[C:%.*]] = and i1 [[A]], [[B]]
@@ -250,21 +257,6 @@ define i32 @select_or_icmp_alt_bad_1(i32 %x, i32 %y, i32 %z) {
define i32 @select_or_icmp_alt_bad_2(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @select_or_icmp_alt_bad_2(
-; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], [[Z:%.*]]
-; CHECK-NEXT: [[B:%.*]] = icmp eq i32 [[Y:%.*]], [[Z]]
-; CHECK-NEXT: [[C:%.*]] = or i1 [[A]], [[B]]
-; CHECK-NEXT: [[D:%.*]] = select i1 [[C]], i32 [[X]], i32 [[Z]]
-; CHECK-NEXT: ret i32 [[D]]
-;
- %A = icmp ne i32 %x, %z
- %B = icmp eq i32 %y, %z
- %C = or i1 %A, %B
- %D = select i1 %C, i32 %x, i32 %z
- ret i32 %D
-}
-
-define i32 @select_or_icmp_alt_bad_3(i32 %x, i32 %y, i32 %z) {
-; CHECK-LABEL: @select_or_icmp_alt_bad_3(
; CHECK-NEXT: [[A:%.*]] = icmp eq i32 [[X:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = icmp eq i32 [[Y:%.*]], [[Z]]
; CHECK-NEXT: [[C:%.*]] = or i1 [[A]], [[B]]
@@ -278,8 +270,8 @@ define i32 @select_or_icmp_alt_bad_3(i32 %x, i32 %y, i32 %z) {
ret i32 %D
}
-define i32 @select_or_icmp_alt_bad_4(i32 %x, i32 %y, i32 %z) {
-; CHECK-LABEL: @select_or_icmp_alt_bad_4(
+define i32 @select_or_icmp_alt_bad_3(i32 %x, i32 %y, i32 %z) {
+; CHECK-LABEL: @select_or_icmp_alt_bad_3(
; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[B:%.*]] = icmp ne i32 [[Y:%.*]], [[Z]]
; CHECK-NEXT: [[C:%.*]] = and i1 [[A]], [[B]]
@@ -293,8 +285,8 @@ define i32 @select_or_icmp_alt_bad_4(i32 %x, i32 %y, i32 %z) {
ret i32 %D
}
-define i32 @select_or_icmp_alt_bad_5(i32 %x, i32 %y, i32 %z, i32 %k) {
-; CHECK-LABEL: @select_or_icmp_alt_bad_5(
+define i32 @select_or_icmp_alt_bad_4(i32 %x, i32 %y, i32 %z, i32 %k) {
+; CHECK-LABEL: @select_or_icmp_alt_bad_4(
; CHECK-NEXT: [[A:%.*]] = icmp ne i32 [[X:%.*]], [[K:%.*]]
; CHECK-NEXT: [[B:%.*]] = icmp ne i32 [[Y:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[C:%.*]] = or i1 [[A]], [[B]]
``````````
</details>
https://github.com/llvm/llvm-project/pull/76363
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