[LLVMdev] Is va_arg deprecated?

[Neal N. Wang]

Hi folk,

I'm writing a set of small C code to verify whether my pass handle some
instruction correctly.   One of the instruction I want to test is "va_arg",
but compiling my variadic function does not generate any va_arg instruction.
Is va_arg deprecated? Will va_arg instruction ever be generated by any
front-end?  The source code and llvm instructions are appended as follows.

the c code
#include<stdarg.h>
#include<stdio.h>
#include<stdlib.h>

void printValue(char * fmt, ...) {
  va_list args;
  va_start(args, fmt);
  int i;
  double d;
  i = va_arg(args, int);
  d = va_arg(args, double);
  va_end(args);
}

the generated llvm instructions:
; ModuleID = 'i.bc'
target datalayout =
"e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
target triple = "i386-pc-linux-gnu"

define void @printValue(i8* %fmt, ...) nounwind {
entry:
  %fmt_addr = alloca i8*                          ; <i8**> [#uses=1]
  %args.2 = alloca i8*                            ; <i8**> [#uses=3]
  %args.0 = alloca i8*                            ; <i8**> [#uses=3]
  %args = alloca i8*                              ; <i8**> [#uses=6]
  %i = alloca i32                                 ; <i32*> [#uses=1]
  %d = alloca double, align 8                     ; <double*> [#uses=1]
  %"alloca point" = bitcast i32 0 to i32          ; <i32> [#uses=0]
  store i8* %fmt, i8** %fmt_addr
  %args1 = bitcast i8** %args to i8*              ; <i8*> [#uses=1]
  call void @llvm.va_start(i8* %args1)
  %0 = load i8** %args, align 4                   ; <i8*> [#uses=1]
  store i8* %0, i8** %args.0, align 4
  %1 = load i8** %args.0, align 4                 ; <i8*> [#uses=1]
  %2 = getelementptr inbounds i8* %1, i64 4       ; <i8*> [#uses=1]
  store i8* %2, i8** %args, align 4
  %3 = load i8** %args.0, align 4                 ; <i8*> [#uses=1]
  %4 = bitcast i8* %3 to i32*                     ; <i32*> [#uses=1]
  %5 = load i32* %4, align 4                      ; <i32> [#uses=1]
  store i32 %5, i32* %i, align 4
  %6 = load i8** %args, align 4                   ; <i8*> [#uses=1]
  store i8* %6, i8** %args.2, align 4
  %7 = load i8** %args.2, align 4                 ; <i8*> [#uses=1]
  %8 = getelementptr inbounds i8* %7, i64 8       ; <i8*> [#uses=1]
  store i8* %8, i8** %args, align 4
  %9 = load i8** %args.2, align 4                 ; <i8*> [#uses=1]
  %10 = bitcast i8* %9 to double*                 ; <double*> [#uses=1]
  %11 = load double* %10, align 4                 ; <double> [#uses=1]
  store double %11, double* %d, align 8
  %args2 = bitcast i8** %args to i8*              ; <i8*> [#uses=1]
  call void @llvm.va_end(i8* %args2)
  br label %return

return:                                           ; preds = %entry
  ret void
}

declare void @llvm.va_start(i8*) nounwind

declare void @llvm.va_end(i8*) nounwind
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20100719/0feb9865/attachment.html>