This is the first patch to put the needed bits in place to eventually allow code
to be aligned with optimal nops. This patch does not change any functionality
and when the compiler is changed to use EmitCodeAlignment() it should also not
change the resulting output. Once the compiler change is made and everything
looks good the next patch with the table of optimal X86 nops will be added to
WriteNopData() changing the output. There are many FIXMEs in this patch which
will be removed when we have better target hooks (coming soon I hear).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96963 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/MC/MCMachOStreamer.cpp b/lib/MC/MCMachOStreamer.cpp
index 797be86..a7a8a5d 100644
--- a/lib/MC/MCMachOStreamer.cpp
+++ b/lib/MC/MCMachOStreamer.cpp
@@ -137,6 +137,8 @@
virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
unsigned ValueSize = 1,
unsigned MaxBytesToEmit = 0);
+ virtual void EmitCodeAlignment(unsigned ByteAlignment,
+ unsigned MaxBytesToEmit = 0);
virtual void EmitValueToOffset(const MCExpr *Offset,
unsigned char Value = 0);
@@ -357,7 +359,20 @@
if (MaxBytesToEmit == 0)
MaxBytesToEmit = ByteAlignment;
new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
- CurSectionData);
+ false /* EmitNops */, CurSectionData);
+
+ // Update the maximum alignment on the current section if necessary.
+ if (ByteAlignment > CurSectionData->getAlignment())
+ CurSectionData->setAlignment(ByteAlignment);
+}
+
+void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
+ unsigned MaxBytesToEmit) {
+ if (MaxBytesToEmit == 0)
+ MaxBytesToEmit = ByteAlignment;
+ // FIXME the 0x90 is the default x86 1 byte nop opcode.
+ new MCAlignFragment(ByteAlignment, 0x90, 1, MaxBytesToEmit,
+ true /* EmitNops */, CurSectionData);
// Update the maximum alignment on the current section if necessary.
if (ByteAlignment > CurSectionData->getAlignment())