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

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

fixes #128778

Author: andjo403

llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp

@@ -3347,12 +3347,6 @@ 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;
@@ -3527,6 +3521,13 @@ 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))

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

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