llvm-project/llvm/test/Transforms/DeadArgElim/keepalive.ll

; RUN: opt < %s -deadargelim -S | FileCheck %s

%Ty = type <{ i32, i32 }>

; Check if the pass doesn't modify anything that doesn't need changing. We feed
; an unused argument to each function to lure it into changing _something_ about
; the function and then changing too much.

; This checks if the return value attributes are not removed
; CHECK: define internal zeroext i32 @test1() #0
define internal zeroext i32 @test1(i32 %DEADARG1) nounwind {
        ret i32 1
}

; This checks if the struct doesn't get non-packed
; CHECK-LABEL: define internal <{ i32, i32 }> @test2(
define internal <{ i32, i32 }> @test2(i32 %DEADARG1) {
        ret <{ i32, i32 }> <{ i32 1, i32 2 }>
}

; We use this external function to make sure the return values don't become dead
declare void @user(i32, <{ i32, i32 }>)

define void @caller() {
        %B = call i32 @test1(i32 1)
        %C = call <{ i32, i32 }> @test2(i32 2)
        call void @user(i32 %B, <{ i32, i32 }> %C)
        ret void
}

; We can't remove 'this' here, as that would put argmem in ecx instead of
; memory.
define internal x86_thiscallcc i32 @unused_this(i32* %this, i32* inalloca %argmem) {
	%v = load i32, i32* %argmem
	ret i32 %v
}
; CHECK-LABEL: define internal x86_thiscallcc i32 @unused_this(i32* %this, i32* inalloca %argmem)

define i32 @caller2() {
	%t = alloca i32
	%m = alloca inalloca i32
	store i32 42, i32* %m
	%v = call x86_thiscallcc i32 @unused_this(i32* %t, i32* inalloca %m)
	ret i32 %v
}

; CHECK: attributes #0 = { nounwind }