[llvm] [InstCombine] handle trunc to i1 in foldLogOpOfMaskedICmps. (PR #128861)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Andreas Jonson (andjo403)

<details>
<summary>Changes</summary>


proof: https://alive2.llvm.org/ce/z/pu8WmX

fixes #<!-- -->128778

---
Full diff: https://github.com/llvm/llvm-project/pull/128861.diff


3 Files Affected:

- (modified) llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (+7-6) 
- (modified) llvm/test/Transforms/InstCombine/eq-of-parts.ll (+2-4) 
- (modified) llvm/test/Transforms/InstCombine/onehot_merge.ll (+6-9) 


``````````diff
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 4616ea6ab5487..3649626d18e14 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -3336,12 +3336,6 @@ Value *InstCombinerImpl::foldAndOrOfICmps(ICmpInst *LHS, ICmpInst *RHS,
     }
   }
 
-  // handle (roughly):
-  // (icmp ne (A & B), C) | (icmp ne (A & D), E)
-  // (icmp eq (A & B), C) & (icmp eq (A & D), E)
-  if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, IsAnd, IsLogical, Builder, Q))
-    return V;
-
   if (Value *V =
           foldAndOrOfICmpEqConstantAndICmp(LHS, RHS, IsAnd, IsLogical, Builder))
     return V;
@@ -3516,6 +3510,13 @@ Value *InstCombinerImpl::foldBooleanAndOr(Value *LHS, Value *RHS,
   if (!LHS->getType()->isIntOrIntVectorTy(1))
     return nullptr;
 
+  // handle (roughly):
+  // (icmp ne (A & B), C) | (icmp ne (A & D), E)
+  // (icmp eq (A & B), C) & (icmp eq (A & D), E)
+  if (Value *V = foldLogOpOfMaskedICmps(LHS, RHS, IsAnd, IsLogical, Builder,
+                                        SQ.getWithInstruction(&I)))
+    return V;
+
   if (auto *LHSCmp = dyn_cast<ICmpInst>(LHS))
     if (auto *RHSCmp = dyn_cast<ICmpInst>(RHS))
       if (Value *Res = foldAndOrOfICmps(LHSCmp, RHSCmp, I, IsAnd, IsLogical))
diff --git a/llvm/test/Transforms/InstCombine/eq-of-parts.ll b/llvm/test/Transforms/InstCombine/eq-of-parts.ll
index d07c2e6a5be52..4dc502788db47 100644
--- a/llvm/test/Transforms/InstCombine/eq-of-parts.ll
+++ b/llvm/test/Transforms/InstCombine/eq-of-parts.ll
@@ -1455,10 +1455,8 @@ define i1 @and_trunc_i1(i8 %a1, i8 %a2) {
 define i1 @and_trunc_i1_wrong_const(i8 %a1, i8 %a2) {
 ; CHECK-LABEL: @and_trunc_i1_wrong_const(
 ; CHECK-NEXT:    [[XOR:%.*]] = xor i8 [[A1:%.*]], [[A2:%.*]]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i8 [[XOR]], 4
-; CHECK-NEXT:    [[LOBIT:%.*]] = trunc i8 [[XOR]] to i1
-; CHECK-NEXT:    [[LOBIT_INV:%.*]] = xor i1 [[LOBIT]], true
-; CHECK-NEXT:    [[AND:%.*]] = and i1 [[CMP]], [[LOBIT_INV]]
+; CHECK-NEXT:    [[TMP1:%.*]] = and i8 [[XOR]], -3
+; CHECK-NEXT:    [[AND:%.*]] = icmp eq i8 [[TMP1]], 0
 ; CHECK-NEXT:    ret i1 [[AND]]
 ;
   %xor = xor i8 %a1, %a2
diff --git a/llvm/test/Transforms/InstCombine/onehot_merge.ll b/llvm/test/Transforms/InstCombine/onehot_merge.ll
index e60edc7315d46..33e39d78e1ce4 100644
--- a/llvm/test/Transforms/InstCombine/onehot_merge.ll
+++ b/llvm/test/Transforms/InstCombine/onehot_merge.ll
@@ -1163,10 +1163,9 @@ define i1 @two_types_of_bittest(i8 %x, i8 %c) {
 define i1 @trunc_bittest_and_icmp_bittest(i8 %x, i8 %c) {
 ; CHECK-LABEL: @trunc_bittest_and_icmp_bittest(
 ; CHECK-NEXT:    [[T0:%.*]] = shl nuw i8 1, [[C:%.*]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i8 [[X:%.*]] to i1
-; CHECK-NEXT:    [[AND:%.*]] = and i8 [[X]], [[T0]]
-; CHECK-NEXT:    [[ICMP2:%.*]] = icmp ne i8 [[AND]], 0
-; CHECK-NEXT:    [[RET:%.*]] = and i1 [[ICMP2]], [[TRUNC]]
+; CHECK-NEXT:    [[TMP1:%.*]] = or i8 [[T0]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = and i8 [[X:%.*]], [[TMP1]]
+; CHECK-NEXT:    [[RET:%.*]] = icmp eq i8 [[TMP2]], [[TMP1]]
 ; CHECK-NEXT:    ret i1 [[RET]]
 ;
   %t0 = shl i8 1, %c
@@ -1180,11 +1179,9 @@ define i1 @trunc_bittest_and_icmp_bittest(i8 %x, i8 %c) {
 define i1 @trunc_bittest_or_icmp_bittest(i8 %x, i8 %c) {
 ; CHECK-LABEL: @trunc_bittest_or_icmp_bittest(
 ; CHECK-NEXT:    [[T0:%.*]] = shl nuw i8 1, [[C:%.*]]
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i8 [[X:%.*]] to i1
-; CHECK-NEXT:    [[AND:%.*]] = and i8 [[X]], [[T0]]
-; CHECK-NEXT:    [[ICMP2:%.*]] = icmp eq i8 [[AND]], 0
-; CHECK-NEXT:    [[NOT:%.*]] = xor i1 [[TRUNC]], true
-; CHECK-NEXT:    [[RET:%.*]] = or i1 [[ICMP2]], [[NOT]]
+; CHECK-NEXT:    [[TMP1:%.*]] = or i8 [[T0]], 1
+; CHECK-NEXT:    [[TMP2:%.*]] = and i8 [[X:%.*]], [[TMP1]]
+; CHECK-NEXT:    [[RET:%.*]] = icmp ne i8 [[TMP2]], [[TMP1]]
 ; CHECK-NEXT:    ret i1 [[RET]]
 ;
   %t0 = shl i8 1, %c

``````````

</details>


https://github.com/llvm/llvm-project/pull/128861