[llvm-dev] How to optimize out the duplicated memory load instructions?

[Terry Guo via llvm-dev]

Hi there,

The raw input IR is composed by my tool and the below one is produced by
llvm opt tool with O3 optimization level. I am pretty sure that the two
load instructions( %mem_base60  and  %mem_base66) are referring to the same
memory location. How can I instruct llvm optimization pass to optimize out
the  %mem_base66 and make the subsequent code reuse the  %mem_base60? I
tried with metadata 'alias.scope' and 'noalias' and it doesn't help. Thanks
for any advice.

392542 check_exce_succ59:                                ; preds =
%check_exce_succ40
**392543   %mem_base60 = load i8*, i8** %mem_base_addr_ptr, align 8
392544   %offset161 = add i32 %call56, 4
392545   %11 = sext i32 %offset161 to i64
392546   %maddr62 = getelementptr inbounds i8, i8* %mem_base60, i64 %11
392547   %data_ptr63 = bitcast i8* %maddr62 to i64*
392548   store i64 0, i64* %data_ptr63, align 8
**392549   %mem_base66 = load i8*, i8** %mem_base_addr_ptr, align 8
392550   %offset167 = add i32 %call56, 12
392551   %12 = sext i32 %offset167 to i64
392552   %maddr68 = getelementptr inbounds i8, i8* %mem_base66, i64 %12
392553   %data_ptr69 = bitcast i8* %maddr68 to i32*
392554   store i32 %call, i32* %data_ptr69, align 8

BR,
Terry
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