[llvm] [ValueTracking] Handle non-canonical operand order in `isImpliedCondICmps` (PR #85575)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-analysis

Author: None (goldsteinn)

<details>
<summary>Changes</summary>

We don't always have canonical order here, so do it manually.


---
Full diff: https://github.com/llvm/llvm-project/pull/85575.diff


4 Files Affected:

- (modified) llvm/lib/Analysis/ValueTracking.cpp (+9) 
- (modified) llvm/test/Transforms/InstCombine/assume.ll (+1-1) 
- (modified) llvm/test/Transforms/InstCombine/select.ll (+2-4) 
- (modified) llvm/test/Transforms/InstCombine/shift.ll (+3-4) 


``````````diff
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index edbeede910d7f7..4d85e423982fc0 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -8532,6 +8532,15 @@ static std::optional<bool> isImpliedCondICmps(const ICmpInst *LHS,
   CmpInst::Predicate LPred =
       LHSIsTrue ? LHS->getPredicate() : LHS->getInversePredicate();
 
+  // We can have non-canonical operands here so canonicalize constant to L1/R1.
+  if (match(L0, m_ImmConstant())) {
+    std::swap(L0, L1);
+    LPred = ICmpInst::getSwappedPredicate(LPred);
+  }
+  if (match(R0, m_ImmConstant())) {
+    std::swap(R0, R1);
+    RPred = ICmpInst::getSwappedPredicate(RPred);
+  }
   // Can we infer anything when the 0-operands match and the 1-operands are
   // constants (not necessarily matching)?
   const APInt *LC, *RC;
diff --git a/llvm/test/Transforms/InstCombine/assume.ll b/llvm/test/Transforms/InstCombine/assume.ll
index 927f0a86b0a252..87c75fb2b55592 100644
--- a/llvm/test/Transforms/InstCombine/assume.ll
+++ b/llvm/test/Transforms/InstCombine/assume.ll
@@ -386,7 +386,7 @@ define i1 @nonnull5(ptr %a) {
 define i32 @assumption_conflicts_with_known_bits(i32 %a, i32 %b) {
 ; CHECK-LABEL: @assumption_conflicts_with_known_bits(
 ; CHECK-NEXT:    store i1 true, ptr poison, align 1
-; CHECK-NEXT:    ret i32 1
+; CHECK-NEXT:    ret i32 poison
 ;
   %and1 = and i32 %b, 3
   %B1 = lshr i32 %and1, %and1
diff --git a/llvm/test/Transforms/InstCombine/select.ll b/llvm/test/Transforms/InstCombine/select.ll
index a84904106eced4..d9734242a86891 100644
--- a/llvm/test/Transforms/InstCombine/select.ll
+++ b/llvm/test/Transforms/InstCombine/select.ll
@@ -2925,10 +2925,8 @@ define i8 @select_replacement_loop3(i32 noundef %x) {
 
 define i16 @select_replacement_loop4(i16 noundef %p_12) {
 ; CHECK-LABEL: @select_replacement_loop4(
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i16 [[P_12:%.*]], 2
-; CHECK-NEXT:    [[AND1:%.*]] = and i16 [[P_12]], 1
-; CHECK-NEXT:    [[AND2:%.*]] = select i1 [[CMP1]], i16 [[AND1]], i16 0
-; CHECK-NEXT:    [[CMP2:%.*]] = icmp eq i16 [[AND2]], [[P_12]]
+; CHECK-NEXT:    [[AND1:%.*]] = and i16 [[P_12:%.*]], 1
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp ult i16 [[P_12]], 2
 ; CHECK-NEXT:    [[AND3:%.*]] = select i1 [[CMP2]], i16 [[AND1]], i16 0
 ; CHECK-NEXT:    ret i16 [[AND3]]
 ;
diff --git a/llvm/test/Transforms/InstCombine/shift.ll b/llvm/test/Transforms/InstCombine/shift.ll
index 62f32c28683711..bef7fc81a7d1f9 100644
--- a/llvm/test/Transforms/InstCombine/shift.ll
+++ b/llvm/test/Transforms/InstCombine/shift.ll
@@ -1751,12 +1751,11 @@ define void @ashr_out_of_range_1(ptr %A) {
 ; CHECK-NEXT:    [[L:%.*]] = load i177, ptr [[A:%.*]], align 4
 ; CHECK-NEXT:    [[L_FROZEN:%.*]] = freeze i177 [[L]]
 ; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i177 [[L_FROZEN]], -1
-; CHECK-NEXT:    [[B:%.*]] = select i1 [[TMP1]], i177 0, i177 [[L_FROZEN]]
-; CHECK-NEXT:    [[TMP2:%.*]] = trunc i177 [[B]] to i64
+; CHECK-NEXT:    [[TMP6:%.*]] = trunc i177 [[L_FROZEN]] to i64
+; CHECK-NEXT:    [[TMP2:%.*]] = select i1 [[TMP1]], i64 0, i64 [[TMP6]]
 ; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr i177, ptr [[A]], i64 [[TMP2]]
 ; CHECK-NEXT:    [[G11:%.*]] = getelementptr i8, ptr [[TMP3]], i64 -24
-; CHECK-NEXT:    [[C17:%.*]] = icmp sgt i177 [[B]], [[L_FROZEN]]
-; CHECK-NEXT:    [[TMP4:%.*]] = sext i1 [[C17]] to i64
+; CHECK-NEXT:    [[TMP4:%.*]] = sext i1 [[TMP1]] to i64
 ; CHECK-NEXT:    [[G62:%.*]] = getelementptr i177, ptr [[G11]], i64 [[TMP4]]
 ; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i177 [[L_FROZEN]], -1
 ; CHECK-NEXT:    [[B28:%.*]] = select i1 [[TMP5]], i177 0, i177 [[L_FROZEN]]

``````````

</details>


https://github.com/llvm/llvm-project/pull/85575