assigned to @zmodem

Slightly reduced:

$ llc -mcpu=pentium4 a.ll -o -

a.ll:

target datalayout = "e-m:w-p:32:32-i64:64-f80:32-n8:16:32-S32"
target triple = "i686-pc-win32"

%struct.Ptr = type { i32* }
%struct.Arr = type { %struct.anon, i8*, %"struct.Arr::shared_memory_size" }
%struct.anon = type { %struct.anon.0, i32, i32 }
%struct.anon.0 = type { [54 x i8] }
%"struct.Arr::shared_memory_size" = type { i32, i32 }

declare void @​llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture readonly, i32, i32, i1)
declare i8* @​llvm.stacksave()
declare void @​llvm.stackrestore(i8*)
declare void @​f(<{ %struct.Ptr }>* inalloca) #​0

define void @​g(%struct.Arr* %a, %struct.Arr* %b, %struct.Ptr* %p) #​0 {
entry:
%inalloca.spmem = alloca i8*
%aptr = bitcast %struct.Arr* %a to i8*
%bptr = bitcast %struct.Arr* %b to i8*
%pptr = bitcast %struct.Ptr* %p to i8*
call void @​llvm.memcpy.p0i8.p0i8.i32(i8* %aptr, i8* %bptr, i32 76, i32 4, i1 false)
%inalloca.save = call i8* @​llvm.stacksave()
%argmem = alloca <{ %struct.Ptr }>, inalloca
store i8* %inalloca.save, i8** %inalloca.spmem
%gep = getelementptr inbounds <{ %struct.Ptr }>* %argmem, i32 0, i32 0
%gepptr = bitcast %struct.Ptr* %gep to i8*
call void @​llvm.memcpy.p0i8.p0i8.i32(i8* %gepptr, i8* %pptr, i32 4, i32 4, i1 false)
call void @​f(<{ %struct.Ptr }>* inalloca %argmem)
call void @​llvm.stackrestore(i8* %inalloca.save)
ret void
}

Should be fixed with r202930.

Hopefully fixed harder in r216775.