LLVM function pointers

C to LLVM

#include <stdio.h>

int add(int i, int j)
{
   return (i + j);
}

int sub(int i, int j)
{
   return (i - j);
}

void print(int x, int y, int (*func)())
{
        printf("value is : %d\n", (*func)(x, y));
}

int main()
{
    int x=100, y=200;
    print(x,y,add);
    print(x,y,sub);

    return 0;
}

%%%%%%%%%%%%%%%%%%%%%%%%%%

; ModuleID = 'function-ptr.ll'
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

@.str = private unnamed_addr constant [15 x i8] c"value is : %d\0A\00", align 1

; Function Attrs: nounwind uwtable
define i32 @add(i32 %i, i32 %j) #0 {
entry:
  %add = add nsw i32 %i, %j
  ret i32 %add
}

; Function Attrs: nounwind uwtable
define i32 @sub(i32 %i, i32 %j) #0 {
entry:
  %sub = sub nsw i32 %i, %j
  ret i32 %sub
}

; Function Attrs: nounwind uwtable
define void @print(i32 %x, i32 %y, i32 (i32, i32)* %func) #0 {
entry:
  %call = call i32 %func(i32 %x, i32 %y)
  %call1 = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([15 x i8]* @.str, i32 0, i32 0), i32 %call)
  ret void
}

declare i32 @printf(i8*, ...) #1

; Function Attrs: nounwind uwtable
define i32 @main() #0 {
entry:
  call void @print(i32 100, i32 200, i32 (i32, i32)* @add)
  call void @print(i32 100, i32 200, i32 (i32, i32)* @sub)
  ret i32 0
}

attributes #0 = { nounwind uwtable "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }

!llvm.ident = !{!0}

!0 = !{!"clang version 3.7.0 (trunk 230020)"}

%%%%%%%%%%%%%%%%%%%%%%%%%%

	.text
	.file	"function-ptr-mem2reg.ll"
	.globl	add
	.align	16, 0x90
	.type	add,@function
add:                                    # @add
	.cfi_startproc
# BB#0:                                 # %entry
	pushq	%rbp
.Ltmp0:
	.cfi_def_cfa_offset 16
.Ltmp1:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
.Ltmp2:
	.cfi_def_cfa_register %rbp
                                        # kill: ESI<def> ESI<kill> RSI<def>
                                        # kill: EDI<def> EDI<kill> RDI<def>
	leal	(%rdi,%rsi), %eax
	popq	%rbp
	retq
.Ltmp3:
	.size	add, .Ltmp3-add
	.cfi_endproc

	.globl	sub
	.align	16, 0x90
	.type	sub,@function
sub:                                    # @sub
	.cfi_startproc
# BB#0:                                 # %entry
	pushq	%rbp
.Ltmp4:
	.cfi_def_cfa_offset 16
.Ltmp5:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
.Ltmp6:
	.cfi_def_cfa_register %rbp
	subl	%esi, %edi
	movl	%edi, %eax
	popq	%rbp
	retq
.Ltmp7:
	.size	sub, .Ltmp7-sub
	.cfi_endproc

	.globl	print
	.align	16, 0x90
	.type	print,@function
print:                                  # @print
	.cfi_startproc
# BB#0:                                 # %entry
	pushq	%rbp
.Ltmp8:
	.cfi_def_cfa_offset 16
.Ltmp9:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
.Ltmp10:
	.cfi_def_cfa_register %rbp
	callq	*%rdx
	movl	%eax, %ecx
	movl	$.L.str, %edi
	xorl	%eax, %eax
	movl	%ecx, %esi
	callq	printf
	popq	%rbp
	retq
.Ltmp11:
	.size	print, .Ltmp11-print
	.cfi_endproc

	.globl	main
	.align	16, 0x90
	.type	main,@function
main:                                   # @main
	.cfi_startproc
# BB#0:                                 # %entry
	pushq	%rbp
.Ltmp12:
	.cfi_def_cfa_offset 16
.Ltmp13:
	.cfi_offset %rbp, -16
	movq	%rsp, %rbp
.Ltmp14:
	.cfi_def_cfa_register %rbp
	movl	$100, %edi
	movl	$200, %esi
	movl	$add, %edx
	callq	print
	movl	$100, %edi
	movl	$200, %esi
	movl	$sub, %edx
	callq	print
	xorl	%eax, %eax
	popq	%rbp
	retq
.Ltmp15:
	.size	main, .Ltmp15-main
	.cfi_endproc

	.type	.L.str,@object          # @.str
	.section	.rodata.str1.1,"aMS",@progbits,1
.L.str:
	.asciz	"value is : %d\n"
	.size	.L.str, 15


	.ident	"clang version 3.7.0 (trunk 230020)"
	.section	".note.GNU-stack","",@progbits