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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Incorrect code generation for inlined functions when -Oz flags are specified"
href="https://bugs.llvm.org/show_bug.cgi?id=42776">42776</a>
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<th>Summary</th>
<td>Incorrect code generation for inlined functions when -Oz flags are specified
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>9.0
</td>
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<th>Hardware</th>
<td>Macintosh
</td>
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<th>OS</th>
<td>MacOS X
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>release blocker
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>joan.lluch@icloud.com
</td>
</tr>
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
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<pre>Consider the following code:
inline int inlinedFunc( int a, int ammount )
{
if ( (ammount -= 8) >= 0 )
a = a >> 8;
while ( ammount-- )
a >>= 1;
return a;
}
int useInlined( int a, int b)
{
return inlinedFunc(a,b);
}
The above is compiled like this for the x86 architecture when -Oz is specified:
; ModuleID = 'main.c'
source_filename = "main.c"
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.12.0"
; Function Attrs: minsize nounwind optsize uwtable
define i32 @useInlined(i32 %a, i32 %b) local_unnamed_addr #0 {
entry:
%call = tail call i32 @inlinedFunc(i32 %a, i32 %b) #2
ret i32 %call
}
; Function Attrs: inlinehint minsize nounwind optsize uwtable
declare i32 @inlinedFunc(i32, i32) local_unnamed_addr #1
attributes #0 = { minsize nounwind optsize uwtable
"correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false"
"less-precise-fpmad"="false" "min-legal-vector-width"="0"
"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"="penryn"
"target-features"="+cx16,+cx8,+fxsr,+mmx,+sahf,+sse,+sse2,+sse3,+sse4.1,+ssse3,+x87"
"unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { inlinehint minsize nounwind optsize uwtable
"correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false"
"less-precise-fpmad"="false" "min-legal-vector-width"="0"
"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"="penryn"
"target-features"="+cx16,+cx8,+fxsr,+mmx,+sahf,+sse,+sse2,+sse3,+sse4.1,+ssse3,+x87"
"unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #2 = { minsize optsize }
!llvm.module.flags = !{!0, !1}
!llvm.ident = !{!2}
!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 7, !"PIC Level", i32 2}
!2 = !{!"clang version 9.0.0 (<a href="https://github.com/llvm/llvm-project.git">https://github.com/llvm/llvm-project.git</a>
bd1c1ad50f7ae95068151c492fefd1f8c3a37e6d)"}
Since the -Oz flag is specified, it is expected and correct that the funciton
is not effectivelly inlined. So "inlineFunc" is called as a normal funcion
(this is ok). However, the "inlinedFunc" is declared but not defined. Its
definition should not be removed from the output because it is actually called
by "useInlined" and not defined elsewhere (not ok).
Joan</pre>
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