[llvm-commits] [llvm] r121856 - in /llvm/trunk: lib/MC/MCAssembler.cpp test/MC/MachO/relax-recompute-align.s
Rafael Espindola
rafael.espindola at gmail.com
Tue Dec 14 23:39:29 PST 2010
Author: rafael
Date: Wed Dec 15 01:39:29 2010
New Revision: 121856
URL: http://llvm.org/viewvc/llvm-project?rev=121856&view=rev
Log:
Patch by David Meyer to avoid a O(N^2) behaviour when relaxing fragments.
Since we now don't update addresses so early, we might relax a bit more than
we need to. This is simillar to the issue in PR8467.
Modified:
llvm/trunk/lib/MC/MCAssembler.cpp
llvm/trunk/test/MC/MachO/relax-recompute-align.s
Modified: llvm/trunk/lib/MC/MCAssembler.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCAssembler.cpp?rev=121856&r1=121855&r2=121856&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCAssembler.cpp (original)
+++ llvm/trunk/lib/MC/MCAssembler.cpp Wed Dec 15 01:39:29 2010
@@ -738,6 +738,7 @@
bool WasRelaxed = false;
for (iterator it = begin(), ie = end(); it != ie; ++it) {
MCSectionData &SD = *it;
+ MCFragment *FirstInvalidFragment = NULL;
for (MCSectionData::iterator it2 = SD.begin(),
ie2 = SD.end(); it2 != ie2; ++it2) {
@@ -762,10 +763,12 @@
break;
}
// Update the layout, and remember that we relaxed.
- if (relaxedFrag)
- Layout.Invalidate(it2);
+ if (relaxedFrag && !FirstInvalidFragment)
+ FirstInvalidFragment = it2;
WasRelaxed |= relaxedFrag;
}
+ if (FirstInvalidFragment)
+ Layout.Invalidate(FirstInvalidFragment);
}
return WasRelaxed;
Modified: llvm/trunk/test/MC/MachO/relax-recompute-align.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/MachO/relax-recompute-align.s?rev=121856&r1=121855&r2=121856&view=diff
==============================================================================
--- llvm/trunk/test/MC/MachO/relax-recompute-align.s (original)
+++ llvm/trunk/test/MC/MachO/relax-recompute-align.s Wed Dec 15 01:39:29 2010
@@ -3,16 +3,16 @@
// FIXME: This is a horrible way of checking the output, we need an llvm-mc
// based 'otool'.
-// This is a case where llvm-mc computes a better layout than Darwin 'as'. This
-// issue is that after the first jmp slides, the .align size must be
-// recomputed -- otherwise the second jump will appear to be out-of-range for a
-// 1-byte jump.
+// FIXME: PR8467.
+// There is an unnecessary relaxation here. After the first jmp slides,
+// the .align size could be recomputed so that the second jump will be in range
+// for a 1-byte jump. For performance reasons, this is not currently done.
// CHECK: # Section 0
// CHECK: (('section_name', '__text\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
// CHECK: ('segment_name', '__TEXT\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
// CHECK: ('address', 0)
-// CHECK: ('size', 306)
+// CHECK: ('size', 322)
// CHECK: ('offset', 324)
// CHECK: ('alignment', 4)
// CHECK: ('reloc_offset', 0)
More information about the llvm-commits
mailing list