> On 2017-Feb-13, at 23:10, Subhendu Malakar via cfe-users
> <cfe-users@lists.llvm.org> wrote:
>
> Hi,
> I'm a newbie in LLVM environment.
>
> I'm trying to generate the LLVM IR of a c file using clang. The command line
> argument I'm passing is as :
> "clang -O0 -S -emit-llvm test.c -c -o test.ll"
If you add "-###" to the end of the command-line you can see the raw -cc1
command for the compilation. Depending on your version of clang, you should
see "-discard-value-names" in there. If you repeat the -cc1 command yourself,
skipping that option, you'll get variable names.
If you're compiling clang yourself (it doesn't sound like you are, but just in
case), this -discard-value-names option is *not* passed by default in asserts
builds.
>
> It is generating the LLVM IR properly but I'm not getting the variable names.
> e.g,
>
> for the c file :
> #include <stdio.h>
>
> int main()
> {
> int x;
> int y;
> x = 2;
> y =4;
> int z = x*y;
>
> if(x==y)
> {
> z = x*y;
> return z;
> } else
> {
> z = x+y;
> }
> printf("z = %d", z);
> return 0;
> }
>
>
> the corresponding llvm IR is :
>
> ; Function Attrs: nounwind uwtable
> define i32 @main() #0 {
> %1 = alloca i32, align 4
> %2 = alloca i32, align 4
> %3 = alloca i32, align 4
> %4 = alloca i32, align 4
> store i32 0, i32* %1, align 4
> store i32 2, i32* %2, align 4
> store i32 4, i32* %3, align 4
> %5 = load i32, i32* %2, align 4
> %6 = load i32, i32* %3, align 4
> %7 = mul nsw i32 %5, %6
> store i32 %7, i32* %4, align 4
> %8 = load i32, i32* %2, align 4
> %9 = load i32, i32* %3, align 4
> %10 = icmp eq i32 %8, %9
> br i1 %10, label %11, label %16
>
> ; <label>:11: ; preds = %0
> %12 = load i32, i32* %2, align 4
> %13 = load i32, i32* %3, align 4
> %14 = mul nsw i32 %12, %13
> store i32 %14, i32* %4, align 4
> %15 = load i32, i32* %4, align 4
> store i32 %15, i32* %1, align 4
> br label %21
>
> ; <label>:16: ; preds = %0
> %17 = load i32, i32* %2, align 4
> %18 = load i32, i32* %3, align 4
> %19 = add nsw i32 %17, %18
> store i32 %19, i32* %4, align 4
> br label %20
>
> ; <label>:20: ; preds = %16
> store i32 0, i32* %1, align 4
> br label %21
>
> ; <label>:21: ; preds = %20, %11
> %22 = load i32, i32* %1, align 4
> ret i32 %22
> }
>
>
> I wanted to get the variables in their original name i.e, x,y,z instead of
> %1,%2,%3, etc.
> Is it possible to do so?
>
> Thanks.
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