[llvm] [InstCombine] Simplify phi using KnownBits of condition (PR #134712)

[David Green via llvm-commits]

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@@ -70,11 +70,10 @@ define i64 @add_i32_i64(ptr nocapture readonly %x, i32 %n) #0 {
 ; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[N]], [[N_VEC]]
 ; CHECK-NEXT:    br i1 [[CMP_N]], label [[FOR_COND_CLEANUP]], label [[SCALAR_PH]]
 ; CHECK:       scalar.ph:
-; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[FOR_BODY_PREHEADER]] ]
 ; CHECK-NEXT:    [[BC_MERGE_RDX:%.*]] = phi i64 [ [[TMP3]], [[MIDDLE_BLOCK]] ], [ 0, [[FOR_BODY_PREHEADER]] ]
 ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
 ; CHECK:       for.body:
-; CHECK-NEXT:    [[I_08:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_BODY]] ], [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ]
+; CHECK-NEXT:    [[I_08:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_BODY]] ], [ 0, [[SCALAR_PH]] ]
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davemgreen wrote:

Are you sure this is correct, if it is coming from middle.block via the vectorized body?

https://github.com/llvm/llvm-project/pull/134712