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<p><font face="Hack Nerd Font Mono">Because in the first case the
GEP is an instruction and in the second case a Constant.</font></p>
<p><font face="Hack Nerd Font Mono">We have helpers, like
GEPOperand, to handle both the same way.<br>
</font></p>
<p><font face="Hack Nerd Font Mono"></font><br>
</p>
<div class="moz-cite-prefix">On 6/13/20 10:29 AM, James
Courtier-Dutton wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAAMvbhF29EXfEay8owsGN1cskSRGdMcDyuN7c5zV5=Sug2gFFA@mail.gmail.com">
<pre class="moz-quote-pre" wrap="">Hi,
What I meant was, why is it not represented by something like this instead:
define dso_local i32 @test21() #0 {
%1 = i8* getelementptr inbounds ([8 x
i8], [8 x i8]* @.str, i64 0, i64 0)
%2 = call i32 (i8*, ...) @printf(%1)
ret i32 0
}
instead of:
define dso_local i32 @test21() #0 {
%1 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([8 x
i8], [8 x i8]* @.str, i64 0, i64 0))
ret i32 0
}
Some code I am writing would be a lot simpler if the first case was used.
On Sun, 31 May 2020 at 16:56, Johannes Doerfert
<a class="moz-txt-link-rfc2396E" href="mailto:johannesdoerfert@gmail.com"><johannesdoerfert@gmail.com></a> wrote:
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">
Hi James,
Like other constant expressions, e.g., i32 0, this GEP constant
expression are "shown" inlined. Constants are unique and exist
everywhere. I guess the most "important' use case I can think
of is to use such GEPs as part of other constant expressions,
e.g., initializers of constant globals.
Cheers,
Johannes
On 5/31/20 3:49 AM, James Courtier-Dutton via llvm-dev wrote:
Hi,
Why is the getelementptr part of the call instruction, instead of
being a separate instruction in the LLVM IR ?
The LLVM IR Builder adds it as a separate instruction, but it is
rolled into one call instruction in the .bc output.
I am just curious as to why it is done this way.
#include <stdint.h>
#include <stdio.h>
int test21(void);
int test21(void) {
printf("Hello1\n");
return 0;
}
define dso_local i32 @test21() #0 {
%1 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([8 x
i8], [8 x i8]* @.str, i64 0, i64 0))
ret i32 0
}
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</pre>
</blockquote>
</blockquote>
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