[llvm] b80f31c - [InstSimplify] with logical ops: (X | Y) ? 0 : X --> 0
via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 25 06:52:41 PDT 2023
Author: Zhongyunde
Date: 2023-04-25T21:51:41+08:00
New Revision: b80f31c48d63743ece1062f30d5f747a03ee5695
URL: https://github.com/llvm/llvm-project/commit/b80f31c48d63743ece1062f30d5f747a03ee5695
DIFF: https://github.com/llvm/llvm-project/commit/b80f31c48d63743ece1062f30d5f747a03ee5695.diff
LOG: [InstSimplify] with logical ops: (X | Y) ? 0 : X --> 0
Use simplifySelectWithICmpEq to handle the implied equalities from the icmp-or,
then both of ICMP_NE and ICMP_EQ will be addressed
(X | Y) == 0 ? X : 0 --> 0 (commuted 2 ways)
(X | Y) != 0 ? 0 : X --> 0 (commuted 2 ways)
Fixes https://github.com/llvm/llvm-project/issues/62263
Reviewed By: nikic, RKSimon
Differential Revision: https://reviews.llvm.org/D148986
Added:
Modified:
llvm/lib/Analysis/InstructionSimplify.cpp
llvm/test/Transforms/InstSimplify/select_or_and.ll
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/InstructionSimplify.cpp b/llvm/lib/Analysis/InstructionSimplify.cpp
index f45ad9829e90..57cfef4e785c 100644
--- a/llvm/lib/Analysis/InstructionSimplify.cpp
+++ b/llvm/lib/Analysis/InstructionSimplify.cpp
@@ -4436,6 +4436,24 @@ static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS,
Pred == ICmpInst::ICMP_EQ);
}
+/// Try to simplify a select instruction when its condition operand is an
+/// integer equality comparison.
+static Value *simplifySelectWithICmpEq(Value *CmpLHS, Value *CmpRHS,
+ Value *TrueVal, Value *FalseVal,
+ const SimplifyQuery &Q,
+ unsigned MaxRecurse) {
+ if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q,
+ /* AllowRefinement */ false,
+ MaxRecurse) == TrueVal)
+ return FalseVal;
+ if (simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q,
+ /* AllowRefinement */ true,
+ MaxRecurse) == FalseVal)
+ return FalseVal;
+
+ return nullptr;
+}
+
/// Try to simplify a select instruction when its condition operand is an
/// integer comparison.
static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
@@ -4524,30 +4542,31 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal,
// the arms of the select. See if substituting this value into the arm and
// simplifying the result yields the same value as the other arm.
if (Pred == ICmpInst::ICMP_EQ) {
- if (simplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, Q,
- /* AllowRefinement */ false,
- MaxRecurse) == TrueVal ||
- simplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, Q,
- /* AllowRefinement */ false,
- MaxRecurse) == TrueVal)
- return FalseVal;
- if (simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, Q,
- /* AllowRefinement */ true,
- MaxRecurse) == FalseVal ||
- simplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, Q,
- /* AllowRefinement */ true,
- MaxRecurse) == FalseVal)
- return FalseVal;
+ if (Value *V = simplifySelectWithICmpEq(CmpLHS, CmpRHS, TrueVal, FalseVal,
+ Q, MaxRecurse))
+ return V;
+ if (Value *V = simplifySelectWithICmpEq(CmpRHS, CmpLHS, TrueVal, FalseVal,
+ Q, MaxRecurse))
+ return V;
+
+ // select(X | Y == 0 ? X : 0) --> 0 (commuted 2 ways)
+ Value *X;
+ Value *Y;
+ if (match(CmpLHS, m_Or(m_Value(X), m_Value(Y))) &&
+ match(CmpRHS, m_Zero())) {
+ // X | Y == 0 implies X == 0 and Y == 0.
+ if (Value *V = simplifySelectWithICmpEq(X, CmpRHS, TrueVal, FalseVal, Q,
+ MaxRecurse))
+ return V;
+ if (Value *V = simplifySelectWithICmpEq(Y, CmpRHS, TrueVal, FalseVal, Q,
+ MaxRecurse))
+ return V;
+ }
}
if (Pred == ICmpInst::Predicate::ICMP_EQ) {
Value *X;
Value *Y;
- // select(X | Y == 0, X or Y, X | Y) -> X | Y
- if (match(CondVal, m_ICmp(Pred, m_Specific(FalseVal), m_Zero())) &&
- match(FalseVal, m_Or(m_Value(X), m_Value(Y))) &&
- (TrueVal == X || TrueVal == Y))
- return FalseVal;
// select(X & Y == -1, X or Y, X & Y) -> X & Y
if (match(CondVal, m_ICmp(Pred, m_Specific(FalseVal), m_AllOnes())) &&
match(FalseVal, m_And(m_Value(X), m_Value(Y))) &&
diff --git a/llvm/test/Transforms/InstSimplify/select_or_and.ll b/llvm/test/Transforms/InstSimplify/select_or_and.ll
index 63476e2483aa..fcac90be6b3f 100644
--- a/llvm/test/Transforms/InstSimplify/select_or_and.ll
+++ b/llvm/test/Transforms/InstSimplify/select_or_and.ll
@@ -64,10 +64,7 @@ define <4 x i32> @select_or_vec(<4 x i32> %x, <4 x i32> %y) {
; select(Y | X == 0, Y | X, Y)
define i32 @select_or_not_1(i32 %x, i32 %y) {
; CHECK-LABEL: @select_or_not_1(
-; CHECK-NEXT: [[OR:%.*]] = or i32 [[Y:%.*]], [[X:%.*]]
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[OR]], 0
-; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[OR]], i32 [[Y]]
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 [[Y:%.*]]
;
%or = or i32 %y, %x
%cmp = icmp eq i32 %or, 0
@@ -77,10 +74,7 @@ define i32 @select_or_not_1(i32 %x, i32 %y) {
; select(Y | X != 0, Y, Y | X)
define i32 @select_or_not_2(i32 %x, i32 %y) {
; CHECK-LABEL: @select_or_not_2(
-; CHECK-NEXT: [[OR:%.*]] = or i32 [[Y:%.*]], [[X:%.*]]
-; CHECK-NEXT: [[CMP:%.*]] = icmp ne i32 [[OR]], 0
-; CHECK-NEXT: [[RET:%.*]] = select i1 [[CMP]], i32 [[Y]], i32 [[OR]]
-; CHECK-NEXT: ret i32 [[RET]]
+; CHECK-NEXT: ret i32 [[Y:%.*]]
;
%or = or i32 %y, %x
%cmp = icmp ne i32 %or, 0
@@ -209,10 +203,7 @@ define i32 @select_icmp_and_eq(i32 %a, i32 %b) {
; https://alive2.llvm.org/ce/z/hSyCuR
define i32 @select_icmp_or_eq(i32 %a, i32 %b) {
; CHECK-LABEL: @select_icmp_or_eq(
-; CHECK-NEXT: [[OR:%.*]] = or i32 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i32 [[OR]], 0
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[TOBOOL]], i32 [[A]], i32 0
-; CHECK-NEXT: ret i32 [[COND]]
+; CHECK-NEXT: ret i32 0
;
%or = or i32 %a, %b
%tobool = icmp eq i32 %or, 0
@@ -222,10 +213,7 @@ define i32 @select_icmp_or_eq(i32 %a, i32 %b) {
define i32 @select_icmp_or_eq_commuted(i32 %a, i32 %b) {
; CHECK-LABEL: @select_icmp_or_eq_commuted(
-; CHECK-NEXT: [[OR:%.*]] = or i32 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq i32 [[OR]], 0
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[TOBOOL]], i32 [[B]], i32 0
-; CHECK-NEXT: ret i32 [[COND]]
+; CHECK-NEXT: ret i32 0
;
%or = or i32 %a, %b
%tobool = icmp eq i32 %or, 0
@@ -236,10 +224,7 @@ define i32 @select_icmp_or_eq_commuted(i32 %a, i32 %b) {
; https://alive2.llvm.org/ce/z/S_pQek
define <2 x i16> @select_icmp_or_eq_vec(<2 x i16> %a, <2 x i16> %b) {
; CHECK-LABEL: @select_icmp_or_eq_vec(
-; CHECK-NEXT: [[OR:%.*]] = or <2 x i16> [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT: [[TOBOOL:%.*]] = icmp eq <2 x i16> [[OR]], zeroinitializer
-; CHECK-NEXT: [[COND:%.*]] = select <2 x i1> [[TOBOOL]], <2 x i16> [[A]], <2 x i16> zeroinitializer
-; CHECK-NEXT: ret <2 x i16> [[COND]]
+; CHECK-NEXT: ret <2 x i16> zeroinitializer
;
%or = or <2 x i16> %a, %b
%tobool = icmp eq <2 x i16> %or, <i16 0, i16 0>
@@ -250,10 +235,7 @@ define <2 x i16> @select_icmp_or_eq_vec(<2 x i16> %a, <2 x i16> %b) {
; The ne will also be matched
define i32 @select_icmp_or_ne(i32 %a, i32 %b) {
; CHECK-LABEL: @select_icmp_or_ne(
-; CHECK-NEXT: [[OR:%.*]] = or i32 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT: [[TOBOOL:%.*]] = icmp ne i32 [[OR]], 0
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[TOBOOL]], i32 0, i32 [[A]]
-; CHECK-NEXT: ret i32 [[COND]]
+; CHECK-NEXT: ret i32 0
;
%or = or i32 %a, %b
%tobool = icmp ne i32 %or, 0
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