[llvm] [CVP] Flip signedness icmp predicate in use level (PR #69948)

[via llvm-commits]

https://github.com/XChy created https://github.com/llvm/llvm-project/pull/69948

Resolve #69928.
[Alive2 Proof](https://alive2.llvm.org/ce/z/zoqaqf).


>From 05e91a11da9bc645fbd14bbfae2a5d6c5e44eb7a Mon Sep 17 00:00:00 2001
From: XChy <xxs_chy at outlook.com>
Date: Tue, 24 Oct 2023 01:18:33 +0800
Subject: [PATCH 1/2] [CVP][NFC] Precommit for flipping signedness predicate in
 use level

---
 .../CorrelatedValuePropagation/icmp.ll        | 75 +++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
index c4f0ade39942a76..e261eb09214f2b5 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
@@ -1246,3 +1246,78 @@ declare <2 x i8> @llvm.umin.v2i8(<2 x i8>, <2 x i8>)
 declare <2 x i8> @llvm.umax.v2i8(<2 x i8>, <2 x i8>)
 
 attributes #4 = { noreturn }
+
+define i64 @test_select_flip(i64 noundef %arg) {
+; CHECK-LABEL: @test_select_flip(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i64 [[ARG:%.*]], 1000
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i64 [[ARG]], 100
+; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[CMP1]], i1 [[CMP2]], i1 false
+; CHECK-NEXT:    br i1 [[SELECT]], label [[GOOD:%.*]], label [[BAD:%.*]]
+; CHECK:       bad:
+; CHECK-NEXT:    ret i64 1
+; CHECK:       good:
+; CHECK-NEXT:    ret i64 0
+;
+entry:
+  %cmp1 = icmp ult i64 %arg, 1000
+  %cmp2 = icmp slt i64 %arg, 100
+  %select = select i1 %cmp1, i1 %cmp2, i1 false
+  br i1 %select, label %good, label %bad
+
+bad:
+  ret i64 1
+
+good:
+  ret i64 0
+}
+
+define i64 @test_select_flip_fail1(i64 noundef %arg) {
+; CHECK-LABEL: @test_select_flip_fail1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp slt i64 [[ARG:%.*]], 1000
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i64 [[ARG]], 100
+; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[CMP1]], i1 [[CMP2]], i1 false
+; CHECK-NEXT:    br i1 [[SELECT]], label [[GOOD:%.*]], label [[BAD:%.*]]
+; CHECK:       bad:
+; CHECK-NEXT:    ret i64 1
+; CHECK:       good:
+; CHECK-NEXT:    ret i64 0
+;
+entry:
+  %cmp1 = icmp slt i64 %arg, 1000
+  %cmp2 = icmp slt i64 %arg, 100
+  %select = select i1 %cmp1, i1 %cmp2, i1 false
+  br i1 %select, label %good, label %bad
+
+bad:
+  ret i64 1
+
+good:
+  ret i64 0
+}
+
+define i64 @test_select_flip_fail2(i64 noundef %arg) {
+; CHECK-LABEL: @test_select_flip_fail2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i64 [[ARG:%.*]], 1000
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i64 [[ARG]], 100
+; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[CMP1]], i1 false, i1 [[CMP2]]
+; CHECK-NEXT:    br i1 [[SELECT]], label [[GOOD:%.*]], label [[BAD:%.*]]
+; CHECK:       bad:
+; CHECK-NEXT:    ret i64 1
+; CHECK:       good:
+; CHECK-NEXT:    ret i64 0
+;
+entry:
+  %cmp1 = icmp ult i64 %arg, 1000
+  %cmp2 = icmp slt i64 %arg, 100
+  %select = select i1 %cmp1, i1 false, i1 %cmp2
+  br i1 %select, label %good, label %bad
+
+bad:
+  ret i64 1
+
+good:
+  ret i64 0
+}

>From 52fd8917c0bae381a3dd92d4487d87e183affea1 Mon Sep 17 00:00:00 2001
From: XChy <xxs_chy at outlook.com>
Date: Tue, 24 Oct 2023 01:09:33 +0800
Subject: [PATCH 2/2] [CVP] Flip signedness icmp predicate in use level

---
 llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp | 5 +++--
 llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll   | 2 +-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
index 523196e5e6eab71..9043c434313fedc 100644
--- a/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
+++ b/llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
@@ -294,8 +294,9 @@ static bool processICmp(ICmpInst *Cmp, LazyValueInfo *LVI) {
 
   ICmpInst::Predicate UnsignedPred =
       ConstantRange::getEquivalentPredWithFlippedSignedness(
-          Cmp->getPredicate(), LVI->getConstantRange(Cmp->getOperand(0), Cmp),
-          LVI->getConstantRange(Cmp->getOperand(1), Cmp));
+          Cmp->getPredicate(),
+          LVI->getConstantRangeAtUse(Cmp->getOperandUse(0)),
+          LVI->getConstantRangeAtUse(Cmp->getOperandUse(1)));
 
   if (UnsignedPred == ICmpInst::Predicate::BAD_ICMP_PREDICATE)
     return false;
diff --git a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
index e261eb09214f2b5..24acd528e6dcde5 100644
--- a/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
+++ b/llvm/test/Transforms/CorrelatedValuePropagation/icmp.ll
@@ -1251,7 +1251,7 @@ define i64 @test_select_flip(i64 noundef %arg) {
 ; CHECK-LABEL: @test_select_flip(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i64 [[ARG:%.*]], 1000
-; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i64 [[ARG]], 100
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp ult i64 [[ARG]], 100
 ; CHECK-NEXT:    [[SELECT:%.*]] = select i1 [[CMP1]], i1 [[CMP2]], i1 false
 ; CHECK-NEXT:    br i1 [[SELECT]], label [[GOOD:%.*]], label [[BAD:%.*]]
 ; CHECK:       bad: