[PATCH] D17555: [Feedback requested] Implement cold spliting

[David Li via llvm-commits]

davidxl added a comment.

There are quite a few refactoring changes that can be combined and split out. After that this patch can be minimized and becomes easier to review. Can you do the split first?

David


================
Comment at: lib/CodeGen/AsmPrinter/DwarfCFIException.cpp:46
@@ -45,4 +45,3 @@
 void DwarfCFIExceptionBase::markFunctionEnd() {
-  if (shouldEmitCFI)
-    Asm->OutStreamer->EmitCFIEndProc();
+  endFragment();
 
----------------
This can be split (with other refactoring changes) into a NFC patch.

================
Comment at: lib/CodeGen/AsmPrinter/DwarfCFIException.cpp:138
@@ +137,3 @@
+///
+void DwarfCFIException::endFunction(const MachineFunction *) {
+  assert(InFlightCFIs.empty() && "Remaining inflight CFI");
----------------
Is it necessary to move this function above here? seems like an irrelevant change.

================
Comment at: lib/CodeGen/AsmPrinter/DwarfCFIException.cpp:147
@@ -147,3 +146,3 @@
 
-  // Provide LSDA information.
-  if (!shouldEmitLSDA)
+void DwarfCFIException::beginFragment(const MachineBasicBlock *MBB,
+                                      ExceptionSymbolProvider ESP) {
----------------
Another candidate of NFC refactoring.

================
Comment at: lib/MC/MCObjectFileInfo.cpp:78
@@ -77,1 +77,3 @@
                            SectionKind::getText());
+  ColdTextSection // .text.cold
+    = Ctx->getMachOSection("__TEXT", "__text.cold",
----------------
Should this section be created on demand when getColdTextSection() is called?

================
Comment at: lib/MC/MCObjectFileInfo.cpp:448
@@ -443,1 +447,3 @@
 
+  ColdTextSection = Ctx->getELFSection(".text.cold", ELF::SHT_PROGBITS,
+                                       ELF::SHF_EXECINSTR | ELF::SHF_ALLOC);
----------------
use .text.unlikely to be consistent with the name used in function reordering.

================
Comment at: lib/MC/MCStreamer.cpp:258
@@ -240,5 +257,3 @@
 void MCStreamer::EmitCFIStartProc(bool IsSimple) {
-  MCDwarfFrameInfo *CurFrame = getCurrentDwarfFrameInfo();
-  if (CurFrame && !CurFrame->End)
-    report_fatal_error("Starting a frame before finishing the previous one!");
+  assert(!hasUnfinishedDwarfFrameInfo() && "Starting a frame before finishing the previous one!");
 
----------------
This refactor change can go in its own patch. Also this change is not NFC -- the original code report fatal error regardless of whether NDEBUG is defined or not.

================
Comment at: test/CodeGen/X86/coldsplit.ll:1
@@ +1,2 @@
+; RUN: llc -split-cold-code < %s | FileCheck %s
+
----------------
need mtriple (either linux or darwin) -- this does not work on COFF yet.


http://reviews.llvm.org/D17555