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<base href="https://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - X86 call frame optimization should be generalized to support 64-bit targets"
href="https://llvm.org/bugs/show_bug.cgi?id=27241">27241</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>X86 call frame optimization should be generalized to support 64-bit targets
</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>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>david.l.kreitzer@intel.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>On 64-bit Linux, we should use pushes to store outgoing arguments to the stack
just like we do for 32-bits (subject to profitability checks). For example, in
the calls to f2 below, the last 3 arguments could be passed via push.
---- t.ll ----
target triple = "x86_64-unknown-linux-gnu"
define void @f1() {
entry:
tail call void @f2(i32 42, i32 43, i32 44, i32 45, i32 46, i32 47, i32 48,
i32 49, i32 50)
ret void
}
declare void @f2(i32, i32, i32, i32, i32, i32, i32, i32, i32)
--------------
Like this:
---- t.s ----
f1: # @f1
.cfi_startproc
# BB#0: # %entry
pushq %rax
.Ltmp0:
.cfi_def_cfa_offset 16
subq $8, %rsp
.Ltmp1:
.cfi_adjust_cfa_offset 8
movl $42, %edi
movl $43, %esi
movl $44, %edx
movl $45, %ecx
movl $46, %r8d
movl $47, %r9d
pushq $50
.Ltmp2:
.cfi_adjust_cfa_offset 8
pushq $49
.Ltmp3:
.cfi_adjust_cfa_offset 8
pushq $48
.Ltmp4:
.cfi_adjust_cfa_offset 8
callq f2
addq $32, %rsp
.Ltmp5:
.cfi_adjust_cfa_offset -32
popq %rax
retq
-------------</pre>
</div>
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