<html>
<head>
<base href="https://llvm.org/bugs/" />
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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 --- - Parameter register assignments wrong for struct with long doubles"
href="https://llvm.org/bugs/show_bug.cgi?id=23026">23026</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Parameter register assignments wrong for struct with long doubles
</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>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>Backend: PowerPC
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hfinkel@anl.gov
</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>Given this program:
$ cat /tmp/ld1.c
struct ld2 { long double x[2]; };
long double foo1(int n, struct ld2 v) {
return v.x[0];
}
long double foo2i(int n, struct ld2 v) {
return v.x[1];
}
There is a mismatch as demonstrated below. gcc believes that v.x[0] is passed
in r4/r5, while clang believes that they reside in r5/r6. The registers used to
access v.x[1] are also off by one. Unfortunately, we're not self-consistent
here either (when we call these functions, we use the same registers as gcc to
pass in the values -- resulting is raw miscompiles ABI issues aside).
$ clang -O3 -S -o - /tmp/ld1.c
.text
.file "/tmp/ld1.c"
.globl foo1
.align 2
.type foo1,@function
.section .opd,"aw",@progbits
foo1: # @foo1
.align 3
.quad .Lfunc_begin0
.quad .TOC.@tocbase
.quad 0
.text
.Lfunc_begin0:
# BB#0: # %entry
std 5, -24(1)
std 6, -16(1)
nop
lfd 1, -24(1)
lfd 2, -16(1)
blr
.long 0
.quad 0
.Lfunc_end0:
.size foo1, .Lfunc_end0-.Lfunc_begin0
.globl foo2i
.align 2
.type foo2i,@function
.section .opd,"aw",@progbits
foo2i: # @foo2i
.align 3
.quad .Lfunc_begin1
.quad .TOC.@tocbase
.quad 0
.text
.Lfunc_begin1:
# BB#0: # %entry
std 7, -24(1)
std 8, -16(1)
nop
lfd 1, -24(1)
lfd 2, -16(1)
blr
.long 0
.quad 0
.Lfunc_end1:
.size foo2i, .Lfunc_end1-.Lfunc_begin1
.ident "clang version 3.7.0 (trunk 232956) (llvm/trunk 232962)"
.section ".note.GNU-stack","",@progbits
$ gcc -O3 -S -o - /tmp/ld1.c
.file "ld1.c"
.section ".toc","aw"
.section ".text"
.align 2
.p2align 4,,15
.globl foo1
.section ".opd","aw"
.align 3
foo1:
.quad .L.foo1,.TOC.@tocbase
.previous
.type foo1, @function
.L.foo1:
std 4,-32(1)
std 5,-24(1)
lfd 1,-32(1)
lfd 2,-24(1)
blr
.long 0
.byte 0,0,0,0,0,0,0,0
.size foo1,.-.L.foo1
.align 2
.p2align 4,,15
.globl foo2i
.section ".opd","aw"
.align 3
foo2i:
.quad .L.foo2i,.TOC.@tocbase
.previous
.type foo2i, @function
.L.foo2i:
std 6,-16(1)
std 7,-8(1)
lfd 1,-16(1)
lfd 2,-8(1)
blr
.long 0
.byte 0,0,0,0,0,0,0,0
.size foo2i,.-.L.foo2i
.ident "GCC: (GNU) 4.4.7 20120313 (Red Hat 4.4.7-4)"
.section .note.GNU-stack,"",@progbits</pre>
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