[clang] [ValueTracking] Simplify uaddo pattern (PR #65910)
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Sat Sep 16 05:22:48 PDT 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-llvm-transforms
<details>
<summary>Changes</summary>
This patch simplifies the overflow check of unsigned addition.
`a + b <u a` implies `a + b <u b`
`a + b >=u a` implies `a + b >=u b`
Alive2: https://alive2.llvm.org/ce/z/H8oK8n
Fixes #<!-- -->65863.
---
Full diff: https://github.com/llvm/llvm-project/pull/65910.diff
2 Files Affected:
- (modified) llvm/lib/Analysis/ValueTracking.cpp (+23)
- (modified) llvm/test/Transforms/InstSimplify/and-or-implied-cond.ll (+8-24)
``````````diff
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index c4153b824c37e0a..5aaff4ee81be969 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -8291,6 +8291,29 @@ static std::optional<bool> isImpliedCondICmps(const ICmpInst *LHS,
if (L0 == R0 && match(L1, m_APInt(LC)) && match(R1, m_APInt(RC)))
return isImpliedCondCommonOperandWithConstants(LPred, *LC, RPred, *RC);
+ // L0 = R0 = L1 + R1, L0 >=u L1 implies R0 >=u R1, L0 <u L1 implies R0 <u R1
+ if (ICmpInst::isUnsigned(LPred) && ICmpInst::isUnsigned(RPred)) {
+ if (L0 == R1) {
+ std::swap(R0, R1);
+ RPred = ICmpInst::getSwappedPredicate(RPred);
+ }
+ if (L1 == R0) {
+ std::swap(L0, L1);
+ LPred = ICmpInst::getSwappedPredicate(LPred);
+ }
+ if (L1 == R1) {
+ std::swap(L0, L1);
+ LPred = ICmpInst::getSwappedPredicate(LPred);
+ std::swap(R0, R1);
+ RPred = ICmpInst::getSwappedPredicate(RPred);
+ }
+ if (L0 == R0 &&
+ (LPred == ICmpInst::ICMP_UGE || LPred == ICmpInst::ICMP_ULT) &&
+ (RPred == ICmpInst::ICMP_ULT || RPred == ICmpInst::ICMP_UGE) &&
+ match(L0, m_c_Add(m_Specific(L1), m_Specific(R1))))
+ return LPred == RPred;
+ }
+
if (LPred == RPred)
return isImpliedCondOperands(LPred, L0, L1, R0, R1, DL, Depth);
diff --git a/llvm/test/Transforms/InstSimplify/and-or-implied-cond.ll b/llvm/test/Transforms/InstSimplify/and-or-implied-cond.ll
index 4a6610250df559a..df442dd8f185c81 100644
--- a/llvm/test/Transforms/InstSimplify/and-or-implied-cond.ll
+++ b/llvm/test/Transforms/InstSimplify/and-or-implied-cond.ll
@@ -131,9 +131,7 @@ define i1 @uaddo_and(i64 %a, i64 %b){
; CHECK-LABEL: @uaddo_and(
; CHECK-NEXT: [[S:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[COND_A:%.*]] = icmp uge i64 [[S]], [[A]]
-; CHECK-NEXT: [[COND_B:%.*]] = icmp uge i64 [[S]], [[B]]
-; CHECK-NEXT: [[COND:%.*]] = and i1 [[COND_A]], [[COND_B]]
-; CHECK-NEXT: ret i1 [[COND]]
+; CHECK-NEXT: ret i1 [[COND_A]]
;
%s = add i64 %a, %b
%cond_a = icmp uge i64 %s, %a
@@ -146,9 +144,7 @@ define i1 @uaddo_and_commuted1(i64 %a, i64 %b){
; CHECK-LABEL: @uaddo_and_commuted1(
; CHECK-NEXT: [[S:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[COND_A:%.*]] = icmp ule i64 [[A]], [[S]]
-; CHECK-NEXT: [[COND_B:%.*]] = icmp uge i64 [[S]], [[B]]
-; CHECK-NEXT: [[COND:%.*]] = and i1 [[COND_A]], [[COND_B]]
-; CHECK-NEXT: ret i1 [[COND]]
+; CHECK-NEXT: ret i1 [[COND_A]]
;
%s = add i64 %a, %b
%cond_a = icmp ule i64 %a, %s
@@ -161,9 +157,7 @@ define i1 @uaddo_and_commuted2(i64 %a, i64 %b){
; CHECK-LABEL: @uaddo_and_commuted2(
; CHECK-NEXT: [[S:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[COND_A:%.*]] = icmp uge i64 [[S]], [[A]]
-; CHECK-NEXT: [[COND_B:%.*]] = icmp ule i64 [[B]], [[S]]
-; CHECK-NEXT: [[COND:%.*]] = and i1 [[COND_A]], [[COND_B]]
-; CHECK-NEXT: ret i1 [[COND]]
+; CHECK-NEXT: ret i1 [[COND_A]]
;
%s = add i64 %a, %b
%cond_a = icmp uge i64 %s, %a
@@ -176,9 +170,7 @@ define i1 @uaddo_and_commuted3(i64 %a, i64 %b){
; CHECK-LABEL: @uaddo_and_commuted3(
; CHECK-NEXT: [[S:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[COND_A:%.*]] = icmp ule i64 [[A]], [[S]]
-; CHECK-NEXT: [[COND_B:%.*]] = icmp ule i64 [[B]], [[S]]
-; CHECK-NEXT: [[COND:%.*]] = and i1 [[COND_A]], [[COND_B]]
-; CHECK-NEXT: ret i1 [[COND]]
+; CHECK-NEXT: ret i1 [[COND_A]]
;
%s = add i64 %a, %b
%cond_a = icmp ule i64 %a, %s
@@ -191,9 +183,7 @@ define i1 @uaddo_or(i64 %a, i64 %b){
; CHECK-LABEL: @uaddo_or(
; CHECK-NEXT: [[S:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[COND_A:%.*]] = icmp ult i64 [[S]], [[A]]
-; CHECK-NEXT: [[COND_B:%.*]] = icmp ult i64 [[S]], [[B]]
-; CHECK-NEXT: [[COND:%.*]] = or i1 [[COND_A]], [[COND_B]]
-; CHECK-NEXT: ret i1 [[COND]]
+; CHECK-NEXT: ret i1 [[COND_A]]
;
%s = add i64 %a, %b
%cond_a = icmp ult i64 %s, %a
@@ -206,9 +196,7 @@ define i1 @uaddo_or_commuted1(i64 %a, i64 %b){
; CHECK-LABEL: @uaddo_or_commuted1(
; CHECK-NEXT: [[S:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[COND_A:%.*]] = icmp ugt i64 [[A]], [[S]]
-; CHECK-NEXT: [[COND_B:%.*]] = icmp ult i64 [[S]], [[B]]
-; CHECK-NEXT: [[COND:%.*]] = or i1 [[COND_A]], [[COND_B]]
-; CHECK-NEXT: ret i1 [[COND]]
+; CHECK-NEXT: ret i1 [[COND_A]]
;
%s = add i64 %a, %b
%cond_a = icmp ugt i64 %a, %s
@@ -221,9 +209,7 @@ define i1 @uaddo_or_commuted2(i64 %a, i64 %b){
; CHECK-LABEL: @uaddo_or_commuted2(
; CHECK-NEXT: [[S:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[COND_A:%.*]] = icmp ult i64 [[S]], [[A]]
-; CHECK-NEXT: [[COND_B:%.*]] = icmp ugt i64 [[B]], [[S]]
-; CHECK-NEXT: [[COND:%.*]] = or i1 [[COND_A]], [[COND_B]]
-; CHECK-NEXT: ret i1 [[COND]]
+; CHECK-NEXT: ret i1 [[COND_A]]
;
%s = add i64 %a, %b
%cond_a = icmp ult i64 %s, %a
@@ -236,9 +222,7 @@ define i1 @uaddo_or_commuted3(i64 %a, i64 %b){
; CHECK-LABEL: @uaddo_or_commuted3(
; CHECK-NEXT: [[S:%.*]] = add i64 [[A:%.*]], [[B:%.*]]
; CHECK-NEXT: [[COND_A:%.*]] = icmp ugt i64 [[A]], [[S]]
-; CHECK-NEXT: [[COND_B:%.*]] = icmp ugt i64 [[B]], [[S]]
-; CHECK-NEXT: [[COND:%.*]] = or i1 [[COND_A]], [[COND_B]]
-; CHECK-NEXT: ret i1 [[COND]]
+; CHECK-NEXT: ret i1 [[COND_A]]
;
%s = add i64 %a, %b
%cond_a = icmp ugt i64 %a, %s
``````````
</details>
https://github.com/llvm/llvm-project/pull/65910
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