[llvm] [MemCpyOpt] Drop dead `memmove` calls on `memset`'d source data (PR #101930)

[Nikita Popov via llvm-commits]

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@@ -0,0 +1,88 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes=memcpyopt -S %s -verify-memoryssa | FileCheck %s
+
+; Redundant memmove.
+define i32 @test() {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:    [[ARRAY:%.*]] = alloca [26 x i32], align 16
+; CHECK-NEXT:    call void @llvm.memset.p0.i64(ptr noundef nonnull align 16 [[ARRAY]], i8 0, i64 104, i1 false)
+; CHECK-NEXT:    [[ARRAY_IDX:%.*]] = getelementptr inbounds i8, ptr [[ARRAY]], i64 4
+; CHECK-NEXT:    [[VAL:%.*]] = load i32, ptr [[ARRAY]], align 16
+; CHECK-NEXT:    ret i32 [[VAL]]
+;
+  %array = alloca [26 x i32], align 16
+  call void @llvm.memset.p0.i64(ptr noundef nonnull align 16 %array, i8 0, i64 104, i1 false)
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nikic wrote:

Please remove irrelevant attributes like noundef nonnull.

https://github.com/llvm/llvm-project/pull/101930