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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - clang generates wrong module by removing un-inlined function body in -O0"
href="https://bugs.llvm.org/show_bug.cgi?id=36236">36236</a>
</td>
</tr>
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<th>Summary</th>
<td>clang generates wrong module by removing un-inlined function body in -O0
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>LLVM Codegen
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>mohammed.agabaria@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>examine the following code:
test.c:
inline int foo(int idx, int* A) {
A[idx] = 0;
return A[idx] + 7;
}
int main(int argc, char* argv[]) {
int A[100];
int As = foo(0, A);
printf("d = %d\n", As);
return 0;
}
main calls foo which have an inline hint.
when compiling in clang -O0 the module won't have foo anymore although it still
have the call to foo (later this cause the linker to fail of course).
LLVM IR: (./clang -O0 test.c -emit-llvm -S -o a.ll)
Notice that main still call foo but there is no definition for foo in the
module.
; ModuleID = 'test.c'
source_filename = "test.c"
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 [8 x i8] c"d = %d\0A\00", align 1
; Function Attrs: noinline nounwind optnone uwtable
define i32 @main(i32 %argc, i8** %argv) #0 {
entry:
%retval = alloca i32, align 4
%argc.addr = alloca i32, align 4
%argv.addr = alloca i8**, align 8
%A = alloca [100 x i32], align 16
%As = alloca i32, align 4
store i32 0, i32* %retval, align 4
store i32 %argc, i32* %argc.addr, align 4
store i8** %argv, i8*** %argv.addr, align 8
%arraydecay = getelementptr inbounds [100 x i32], [100 x i32]* %A, i32 0, i32
0
%call = call i32 @foo(i32 0, i32* %arraydecay)
store i32 %call, i32* %As, align 4
%0 = load i32, i32* %As, align 4
%call1 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([8 x i8], [8
x i8]* @.str, i32 0, i32 0), i32 %0)
ret i32 0
}
declare i32 @foo(i32, i32*) #1
declare i32 @printf(i8*, ...) #1
attributes #0 = { noinline nounwind optnone uwtable
"correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false"
"less-precise-fpmad"="false" "no-frame-pointer-elim"="true"
"no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false"
"no-jump-tables"="false" "no-nans-fp-math"="false"
"no-signed-zeros-fp-math"="false" "no-trapping-math"="false"
"stack-protector-buffer-size"="8" "target-cpu"="x86-64"
"target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false"
"use-soft-float"="false" }
attributes #1 = { "correctly-rounded-divide-sqrt-fp-math"="false"
"disable-tail-calls"="false" "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"
"no-signed-zeros-fp-math"="false" "no-trapping-math"="false"
"stack-protector-buffer-size"="8" "target-cpu"="x86-64"
"target-features"="+fxsr,+mmx,+sse,+sse2,+x87" "unsafe-fp-math"="false"
"use-soft-float"="false" }
!llvm.module.flags = !{!0}
!llvm.ident = !{!1}
!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{!"clang version 7.0.0 (trunk 324213)"}</pre>
</div>
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