<html>
<head>
<base href="https://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 --- - [IPRA] Failed to mark return address register as clobbered"
href="https://llvm.org/bugs/show_bug.cgi?id=28569">28569</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[IPRA] Failed to mark return address register as clobbered
</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>Register Allocator
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>zyfwong@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>=== ipra-call.c ===
__attribute__((noinline))
int foo2(int b)
{
return b + 2;
}
__attribute__((noinline))
int bar2(int b)
{
return b + foo2(b);
}
$ clang -target arm -Oz -emit-llvm -S ipra-call.c -o ipra-call.ll
$ llc -march=arm ipra-call.ll -enable-ipra=true -print-regusage
bar2 Clobbered Registers: SP R0 R1 R2 R3 R12 R12_SP R0_R1 R2_R3
foo2 Clobbered Registers: R0 R1 R0_R1
===== ipra-call.s =====
foo2: @ @foo2
add r0, r0, #2
mov pc, lr
bar2: @ @bar2
push {r11, lr}
mov r11, sp
mov r2, r0
bl foo2
add r0, r0, r2
pop {r11, lr}
mov pc, lr
I think bar2 should mark LR as Clobbered.
Current implementation thinks that a `call foo' instruction only clobbers
registers that clobbers by function `foo', but it's not true: `call foo' will
clobbers both registers clobbers by function `foo' and other physical registers
, in this case, LR.</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>