Extended Description

Instcombine should eliminate the two bitcasts in this example:

define i8* @​test(i8* %v) {
%A = alloca [4 x i8*], align 16 ; <[4 x i8*]> [#uses=3]
%B = getelementptr [4 x i8]* %A, i32 0, i32 0 ; <i8**> [#uses=1]
store i8* null, i8** %B
%C = bitcast [4 x i8*]* %A to { [16 x i8] }* ; <{ [16 x i8] }> [#uses=1]
%D = getelementptr { [16 x i8] } %C, i32 0, i32 0, i32 8 ; <i8*> [#uses=1]
%E = bitcast i8* %D to i8** ; <i8**> [#uses=1]
store i8* %v, i8** %E
%F = getelementptr [4 x i8*]* %A, i32 0, i32 2 ; <i8**> [#uses=1]
%G = load i8** %F ; <i8*> [#uses=1]
ret i8* %G
}

Doing so would allow SROA to eliminate the alloca, turning the function into an identity function.

-Chris