showing one example of improved LLVM IR for zig self hosted compiler

example.zig

export fn entry() bool {
    doTheTest() catch return false;
    return true;
}

fn doTheTest() !void {
    var x1: u8 = 42;
    const t1 = .{ x1, 56, 54 };
    var arr1: [3]u8 = t1;
    _ = arr1[0];
}

stage1.ll

; Function Attrs: nobuiltin nounwind
define internal fastcc i16 @doTheTest() unnamed_addr #1 {
Entry:
  %result = alloca i16, align 2
  %x1 = alloca i8, align 1
  %t1 = alloca %"struct:24:25", align 1
  %0 = alloca [3 x i8], align 1
  %arr1 = alloca [3 x i8], align 1
  %1 = alloca [3 x i8], align 1
  %2 = alloca [3 x i8], align 1
  store i8 42, i8* %x1, align 1
  %3 = load i8, i8* %x1, align 1
  %4 = getelementptr inbounds %"struct:24:25", %"struct:24:25"* %t1, i32 0, i32 0
  store i8 %3, i8* %4, align 1
  %5 = getelementptr inbounds %"struct:24:25", %"struct:24:25"* %t1, i32 0, i32 0
  %6 = load i8, i8* %5, align 1
  %7 = getelementptr inbounds [3 x i8], [3 x i8]* %0, i64 0, i64 0
  store i8 %6, i8* %7, align 1
  %8 = getelementptr inbounds [3 x i8], [3 x i8]* %0, i64 0, i64 1
  store i8 56, i8* %8, align 1
  %9 = getelementptr inbounds [3 x i8], [3 x i8]* %0, i64 0, i64 2
  store i8 54, i8* %9, align 1
  %10 = getelementptr inbounds %"struct:24:25", %"struct:24:25"* %t1, i32 0, i32 0
  %11 = load i8, i8* %10, align 1
  %12 = getelementptr inbounds [3 x i8], [3 x i8]* %1, i64 0, i64 0
  store i8 %11, i8* %12, align 1
  %13 = getelementptr inbounds [3 x i8], [3 x i8]* %1, i64 0, i64 1
  store i8 56, i8* %13, align 1
  %14 = getelementptr inbounds [3 x i8], [3 x i8]* %1, i64 0, i64 2
  store i8 54, i8* %14, align 1
  %15 = bitcast [3 x i8]* %1 to i8*
  %16 = bitcast [3 x i8]* %arr1 to i8*
  call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 1 %16, i8* align 1 %15, i64 3, i1 false)
  %17 = getelementptr inbounds %"struct:24:25", %"struct:24:25"* %t1, i32 0, i32 0
  %18 = load i8, i8* %17, align 1
  %19 = getelementptr inbounds [3 x i8], [3 x i8]* %2, i64 0, i64 0
  store i8 %18, i8* %19, align 1
  %20 = getelementptr inbounds [3 x i8], [3 x i8]* %2, i64 0, i64 1
  store i8 56, i8* %20, align 1
  %21 = getelementptr inbounds [3 x i8], [3 x i8]* %2, i64 0, i64 2
  store i8 54, i8* %21, align 1
  %22 = getelementptr inbounds [3 x i8], [3 x i8]* %arr1, i64 0, i64 0
  store i16 0, i16* %result, align 2
  ret i16 0
}

stage2.ll

%0 = type { i8 }

; Function Attrs: nounwind
define internal fastcc i16 @doTheTest() unnamed_addr #0 {
Entry:
  %0 = alloca [3 x i8], align 1
  %1 = alloca i8, align 1
  store i8 42, i8* %1, align 1
  %2 = load i8, i8* %1, align 1
  %3 = insertvalue %0 undef, i8 %2, 0
  %4 = extractvalue %0 %3, 0
  %5 = getelementptr inbounds [3 x i8], [3 x i8]* %0, i32 0, i64 0
  store i8 %4, i8* %5, align 1
  %6 = getelementptr inbounds [3 x i8], [3 x i8]* %0, i32 0, i64 1
  store i8 56, i8* %6, align 1
  %7 = getelementptr inbounds [3 x i8], [3 x i8]* %0, i32 0, i64 2
  store i8 54, i8* %7, align 1
  ret i16 0
}