[llvm] [Attributor] Change allocation size and load/store offsets using AAPointerInfo for Alloca instructions (PR #72029)

[Vidush Singhal via llvm-commits]

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@@ -2647,18 +2647,18 @@ define dso_local void @test_nested_memory(ptr %dst, ptr %src) {
 ; TUNIT-SAME: ptr nofree writeonly captures(none) [[DST:%.*]], ptr nofree readonly captures(none) [[SRC:%.*]]) {
 ; TUNIT-NEXT:  [[ENTRY:.*:]]
 ; TUNIT-NEXT:    [[CALL_H2S:%.*]] = alloca i8, i64 24, align 1
-; TUNIT-NEXT:    [[LOCAL:%.*]] = alloca [[STRUCT_STY:%.*]], align 8
-; TUNIT-NEXT:    [[INNER:%.*]] = getelementptr inbounds [[STRUCT_STY]], ptr [[LOCAL]], i64 0, i32 2
-; TUNIT-NEXT:    store ptr @global, ptr [[INNER]], align 8
+; TUNIT-NEXT:    [[LOCAL1:%.*]] = alloca [8 x i8], align 1
+; TUNIT-NEXT:    [[NEWGEP:%.*]] = getelementptr [8 x i8], ptr [[LOCAL1]], i64 0
+; TUNIT-NEXT:    store ptr @global, ptr [[NEWGEP]], align 8
 ; TUNIT-NEXT:    store ptr [[DST]], ptr [[CALL_H2S]], align 8
 ; TUNIT-NEXT:    [[SRC2:%.*]] = getelementptr inbounds i8, ptr [[CALL_H2S]], i64 8
 ; TUNIT-NEXT:    store ptr [[SRC]], ptr [[SRC2]], align 8
-; TUNIT-NEXT:    store ptr [[CALL_H2S]], ptr getelementptr inbounds ([[STRUCT_STY]], ptr @global, i64 0, i32 2), align 8
-; TUNIT-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[LOCAL]], align 8
-; TUNIT-NEXT:    [[LOCAL_B8:%.*]] = getelementptr i8, ptr [[LOCAL]], i64 8
-; TUNIT-NEXT:    [[TMP1:%.*]] = load ptr, ptr [[LOCAL_B8]], align 8
-; TUNIT-NEXT:    [[LOCAL_B16:%.*]] = getelementptr i8, ptr [[LOCAL]], i64 16
-; TUNIT-NEXT:    [[TMP2:%.*]] = load ptr, ptr [[LOCAL_B16]], align 8
+; TUNIT-NEXT:    store ptr [[CALL_H2S]], ptr getelementptr inbounds ([[STRUCT_STY:%.*]], ptr @global, i64 0, i32 2), align 8
+; TUNIT-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[LOCAL1]], align 8
+; TUNIT-NEXT:    [[LOCAL1_B8:%.*]] = getelementptr i8, ptr [[LOCAL1]], i64 8
+; TUNIT-NEXT:    [[TMP1:%.*]] = load ptr, ptr [[LOCAL1_B8]], align 8
+; TUNIT-NEXT:    [[LOCAL1_B16:%.*]] = getelementptr i8, ptr [[LOCAL1]], i64 16
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vidsinghal wrote:

I think this is because, once `AAPrivatizablePtr` is run, `AAPointerInfo` does not not change the accesses that are associated with the pointer. For now i can detect this and give up. Over a separate PR this might be good to investigate and give a fix for this. 
 

https://github.com/llvm/llvm-project/pull/72029