<html>
<head>
<base href="http://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Instcombine removes inalloca flag from alloca instruction"
href="http://llvm.org/bugs/show_bug.cgi?id=19569">19569</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Instcombine removes inalloca flag from alloca instruction
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</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>Scalar Optimizations
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>david.majnemer@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>consider:
; ModuleID = '<stdin>'
target datalayout = "e-m:w-p:32:32-i64:64-f80:32-n8:16:32-S32"
target triple = "i686-pc-windows-msvc"
%struct.gfx_size = type { i32, i32 }
; Function Attrs: nounwind
define void @"\01?doit@@YAXAAUgfx_size@@@Z"(%struct.gfx_size* %a) #0 {
entry:
%inalloca.save = call i8* @llvm.stacksave()
%argmem = alloca inalloca <{ %struct.gfx_size }>
%0 = getelementptr inbounds <{ %struct.gfx_size }>* %argmem, i32 0, i32 0
%1 = bitcast %struct.gfx_size* %0 to i8*
%2 = bitcast %struct.gfx_size* %a to i8*
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %1, i8* %2, i32 8, i32 4, i1 false)
call void @"\01?f@@YAXUgfx_size@@@Z"(<{ %struct.gfx_size }>* inalloca
%argmem)
call void @llvm.stackrestore(i8* %inalloca.save)
ret void
}
declare void @"\01?f@@YAXUgfx_size@@@Z"(<{ %struct.gfx_size }>* inalloca) #1
; Function Attrs: nounwind
declare i8* @llvm.stacksave() #2
; Function Attrs: nounwind
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture readonly,
i32, i32, i1) #2
; Function Attrs: nounwind
declare void @llvm.stackrestore(i8*) #2
attributes #0 = { nounwind "less-precise-fpmad"="false"
"no-frame-pointer-elim"="false" "no-infs-fp-math"="false"
"no-nans-fp-math"="false" "stack-protector-buffer-size"="8"
"unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="false"
"no-infs-fp-math"="false" "no-nans-fp-math"="false"
"stack-protector-buffer-size"="8" "unsafe-fp-math"="false"
"use-soft-float"="false" }
attributes #2 = { nounwind }
!llvm.ident = !{!0}
!0 = metadata !{metadata !"clang version 3.5.0 "}
running with ~/llvm/build/bin/opt -instcombine shows that we will produce the
following IR:
define void @"\01?doit@@YAXAAUgfx_size@@@Z"(%struct.gfx_size* %a) #0 {
entry:
%argmem = alloca i64, align 8
%tmpcast = bitcast i64* %argmem to <{ %struct.gfx_size }>*
%0 = bitcast %struct.gfx_size* %a to i64*
%1 = load i64* %0, align 4
store i64 %1, i64* %argmem, align 8
call void @"\01?f@@YAXUgfx_size@@@Z"(<{ %struct.gfx_size }>* inalloca
%tmpcast) #2
ret void
}
note that we have removed the inalloca marker from our alloca instruction,
dooming the call to @"\01?f@@YAXUgfx_size@@@Z"</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>