[llvm] b4ac7f4 - [InstCombine] Fold `(icmp eq/ne (or (select cond, 0/NZ, 0/NZ), X), 0)`
Noah Goldstein via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 5 08:49:14 PDT 2024
Author: Noah Goldstein
Date: 2024-08-05T23:48:49+08:00
New Revision: b4ac7f4fc91ee5c8a192bcf15fffa69cb30d1912
URL: https://github.com/llvm/llvm-project/commit/b4ac7f4fc91ee5c8a192bcf15fffa69cb30d1912
DIFF: https://github.com/llvm/llvm-project/commit/b4ac7f4fc91ee5c8a192bcf15fffa69cb30d1912.diff
LOG: [InstCombine] Fold `(icmp eq/ne (or (select cond, 0/NZ, 0/NZ), X), 0)`
Four cases:
`(icmp eq (or (select cond, 0, NonZero), Other))`
-> `(and cond, (icmp eq Other, 0))`
`(icmp ne (or (select cond, NonZero, 0), Other))`
-> `(or cond, (icmp ne Other, 0))`
`(icmp ne (or (select cond, 0, NonZero), Other))`
-> `(or (not cond), (icmp ne Other, 0))`
`(icmp eq (or (select cond, NonZero, 0), Other))`
-> `(and (not cond), (icmp eq Other, 0))`
These cases came up in tests on: #88088
Proofs: https://alive2.llvm.org/ce/z/ojGo_J
Closes #88183
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
llvm/test/Transforms/InstCombine/icmp-or-of-select-with-zero.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index 473998bc26000..10a89b47e0753 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3530,6 +3530,52 @@ Instruction *InstCombinerImpl::foldICmpBinOpEqualityWithConstant(
Value *And = Builder.CreateAnd(BOp0, NotBOC);
return new ICmpInst(Pred, And, NotBOC);
}
+ // (icmp eq (or (select cond, 0, NonZero), Other), 0)
+ // -> (and cond, (icmp eq Other, 0))
+ // (icmp ne (or (select cond, NonZero, 0), Other), 0)
+ // -> (or cond, (icmp ne Other, 0))
+ Value *Cond, *TV, *FV, *Other, *Sel;
+ if (C.isZero() &&
+ match(BO,
+ m_OneUse(m_c_Or(m_CombineAnd(m_Value(Sel),
+ m_Select(m_Value(Cond), m_Value(TV),
+ m_Value(FV))),
+ m_Value(Other))))) {
+ const SimplifyQuery Q = SQ.getWithInstruction(&Cmp);
+ // Easy case is if eq/ne matches whether 0 is trueval/falseval.
+ if (Pred == ICmpInst::ICMP_EQ
+ ? (match(TV, m_Zero()) && isKnownNonZero(FV, Q))
+ : (match(FV, m_Zero()) && isKnownNonZero(TV, Q))) {
+ Value *Cmp = Builder.CreateICmp(
+ Pred, Other, Constant::getNullValue(Other->getType()));
+ return BinaryOperator::Create(
+ Pred == ICmpInst::ICMP_EQ ? Instruction::And : Instruction::Or, Cmp,
+ Cond);
+ }
+ // Harder case is if eq/ne matches whether 0 is falseval/trueval. In this
+ // case we need to invert the select condition so we need to be careful to
+ // avoid creating extra instructions.
+ // (icmp ne (or (select cond, 0, NonZero), Other), 0)
+ // -> (or (not cond), (icmp ne Other, 0))
+ // (icmp eq (or (select cond, NonZero, 0), Other), 0)
+ // -> (and (not cond), (icmp eq Other, 0))
+ //
+ // Only do this if the inner select has one use, in which case we are
+ // replacing `select` with `(not cond)`. Otherwise, we will create more
+ // uses. NB: Trying to freely invert cond doesn't make sense here, as if
+ // cond was freely invertable, the select arms would have been inverted.
+ if (Sel->hasOneUse() &&
+ (Pred == ICmpInst::ICMP_EQ
+ ? (match(FV, m_Zero()) && isKnownNonZero(TV, Q))
+ : (match(TV, m_Zero()) && isKnownNonZero(FV, Q)))) {
+ Value *NotCond = Builder.CreateNot(Cond);
+ Value *Cmp = Builder.CreateICmp(
+ Pred, Other, Constant::getNullValue(Other->getType()));
+ return BinaryOperator::Create(
+ Pred == ICmpInst::ICMP_EQ ? Instruction::And : Instruction::Or, Cmp,
+ NotCond);
+ }
+ }
break;
}
case Instruction::UDiv:
diff --git a/llvm/test/Transforms/InstCombine/icmp-or-of-select-with-zero.ll b/llvm/test/Transforms/InstCombine/icmp-or-of-select-with-zero.ll
index 22968bab481c1..90e0461f8b789 100644
--- a/llvm/test/Transforms/InstCombine/icmp-or-of-select-with-zero.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-or-of-select-with-zero.ll
@@ -5,10 +5,8 @@ declare void @use.i8(i8)
declare void @use.i1(i1)
define i1 @src_tv_eq(i1 %c0, i8 %x, i8 %yy) {
; CHECK-LABEL: @src_tv_eq(
-; CHECK-NEXT: [[Y:%.*]] = add nuw i8 [[YY:%.*]], 1
-; CHECK-NEXT: [[SEL:%.*]] = select i1 [[C0:%.*]], i8 0, i8 [[Y]]
-; CHECK-NEXT: [[SELX:%.*]] = or i8 [[SEL]], [[X:%.*]]
-; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[SELX]], 0
+; CHECK-NEXT: [[TMP1:%.*]] = icmp eq i8 [[X:%.*]], 0
+; CHECK-NEXT: [[R:%.*]] = and i1 [[TMP1]], [[C0:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = add nuw i8 %yy, 1
@@ -52,10 +50,8 @@ define i1 @src_tv_eq_fail_tv_nonzero(i1 %c0, i8 %x, i8 %yy) {
define i1 @src_fv_ne(i1 %c0, i8 %x, i8 %yy) {
; CHECK-LABEL: @src_fv_ne(
-; CHECK-NEXT: [[Y:%.*]] = add nuw i8 [[YY:%.*]], 1
-; CHECK-NEXT: [[SEL:%.*]] = select i1 [[C0:%.*]], i8 [[Y]], i8 0
-; CHECK-NEXT: [[SELX:%.*]] = or i8 [[SEL]], [[X:%.*]]
-; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[SELX]], 0
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ne i8 [[X:%.*]], 0
+; CHECK-NEXT: [[R:%.*]] = or i1 [[TMP1]], [[C0:%.*]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = add nuw i8 %yy, 1
@@ -82,10 +78,9 @@ define i1 @src_fv_ne_fail_maybe_zero(i1 %c0, i8 %x, i8 %yy) {
define i1 @src_tv_ne(i1 %c0, i8 %x, i8 %yy) {
; CHECK-LABEL: @src_tv_ne(
-; CHECK-NEXT: [[Y:%.*]] = add nuw i8 [[YY:%.*]], 1
-; CHECK-NEXT: [[SEL:%.*]] = select i1 [[C0:%.*]], i8 0, i8 [[Y]]
-; CHECK-NEXT: [[SELX:%.*]] = or i8 [[SEL]], [[X:%.*]]
-; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[SELX]], 0
+; CHECK-NEXT: [[TMP1:%.*]] = xor i1 [[C0:%.*]], true
+; CHECK-NEXT: [[TMP2:%.*]] = icmp ne i8 [[X:%.*]], 0
+; CHECK-NEXT: [[R:%.*]] = or i1 [[TMP2]], [[TMP1]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = add nuw i8 %yy, 1
@@ -112,10 +107,9 @@ define i1 @src_tv_ne_fail_cmp_nonzero(i1 %c0, i8 %x, i8 %yy) {
define i1 @src_fv_eq(i1 %c0, i8 %x, i8 %yy) {
; CHECK-LABEL: @src_fv_eq(
-; CHECK-NEXT: [[Y:%.*]] = add nuw i8 [[YY:%.*]], 1
-; CHECK-NEXT: [[SEL:%.*]] = select i1 [[C0:%.*]], i8 [[Y]], i8 0
-; CHECK-NEXT: [[SELX:%.*]] = or i8 [[SEL]], [[X:%.*]]
-; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[SELX]], 0
+; CHECK-NEXT: [[TMP1:%.*]] = xor i1 [[C0:%.*]], true
+; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i8 [[X:%.*]], 0
+; CHECK-NEXT: [[R:%.*]] = and i1 [[TMP2]], [[TMP1]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = add nuw i8 %yy, 1
@@ -172,11 +166,11 @@ define i1 @src_fv_eq_invert2(i1 %c1, i8 %a, i8 %b, i8 %x, i8 %yy) {
; CHECK-LABEL: @src_fv_eq_invert2(
; CHECK-NEXT: [[C0:%.*]] = icmp ugt i8 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[Y:%.*]] = add nuw i8 [[YY:%.*]], 1
-; CHECK-NEXT: [[SEL:%.*]] = select i1 [[C0]], i8 [[Y]], i8 0
; CHECK-NEXT: [[CC:%.*]] = or i1 [[C0]], [[C1:%.*]]
; CHECK-NEXT: [[SEL_OTHER:%.*]] = select i1 [[CC]], i8 [[Y]], i8 [[B]]
-; CHECK-NEXT: [[SELX:%.*]] = or i8 [[SEL]], [[X:%.*]]
-; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[SELX]], 0
+; CHECK-NEXT: [[TMP1:%.*]] = xor i1 [[C0]], true
+; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i8 [[X:%.*]], 0
+; CHECK-NEXT: [[R:%.*]] = and i1 [[TMP2]], [[TMP1]]
; CHECK-NEXT: call void @use.i8(i8 [[SEL_OTHER]])
; CHECK-NEXT: ret i1 [[R]]
;
@@ -192,6 +186,9 @@ define i1 @src_fv_eq_invert2(i1 %c1, i8 %a, i8 %b, i8 %x, i8 %yy) {
ret i1 %r
}
+
+
+
define i1 @src_fv_eq_invert2_fail_wrong_binop(i1 %c1, i8 %a, i8 %b, i8 %x, i8 %yy) {
; CHECK-LABEL: @src_fv_eq_invert2_fail_wrong_binop(
; CHECK-NEXT: [[C0:%.*]] = icmp ugt i8 [[A:%.*]], [[B:%.*]]
@@ -266,6 +263,7 @@ define i1 @src_fv_eq_invert3(i8 %a, i8 %b, i8 %x, i8 %yy) {
ret i1 %r
}
+
define i1 @src_tv_ne_invert(i1 %c1, i8 %a, i8 %b, i8 %x, i8 %yy) {
; CHECK-LABEL: @src_tv_ne_invert(
; CHECK-NEXT: [[NOT_C0:%.*]] = icmp ugt i8 [[A:%.*]], [[B:%.*]]
@@ -275,8 +273,8 @@ define i1 @src_tv_ne_invert(i1 %c1, i8 %a, i8 %b, i8 %x, i8 %yy) {
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[NOT_C0]], i8 [[Y]], i8 0
; CHECK-NEXT: [[CC:%.*]] = or i1 [[C0]], [[C1:%.*]]
; CHECK-NEXT: [[SEL_OTHER:%.*]] = select i1 [[CC]], i8 [[Y]], i8 [[B]]
-; CHECK-NEXT: [[SELX:%.*]] = or i8 [[SEL]], [[X:%.*]]
-; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[SELX]], 0
+; CHECK-NEXT: [[TMP1:%.*]] = icmp ne i8 [[X:%.*]], 0
+; CHECK-NEXT: [[R:%.*]] = or i1 [[TMP1]], [[NOT_C0]]
; CHECK-NEXT: call void @use.i8(i8 [[SEL]])
; CHECK-NEXT: call void @use.i8(i8 [[SEL_OTHER]])
; CHECK-NEXT: ret i1 [[R]]
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