[llvm-commits] [llvm] r90163 - in /llvm/trunk: lib/CodeGen/LiveIntervalAnalysis.cpp test/CodeGen/X86/2008-08-05-SpillerBug.ll

[Jakob Stoklund Olesen]

Author: stoklund
Date: Mon Nov 30 16:55:54 2009
New Revision: 90163

URL: http://llvm.org/viewvc/llvm-project?rev=90163&view=rev
Log:
New virtual registers created for spill intervals should inherit allocation hints from the original register.

This helps us avoid silly copies when rematting values that are copied to a physical register:

leaq	_.str44(%rip), %rcx
movq	%rcx, %rsi
call	_strcmp

becomes:

leaq	_.str44(%rip), %rsi
call	_strcmp

The coalescer will not touch the movq because that would tie down the physical register.

Modified:
    llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp
    llvm/trunk/test/CodeGen/X86/2008-08-05-SpillerBug.ll

Modified: llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp?rev=90163&r1=90162&r2=90163&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp (original)
+++ llvm/trunk/lib/CodeGen/LiveIntervalAnalysis.cpp Mon Nov 30 16:55:54 2009
@@ -1095,6 +1095,12 @@
       NewVReg = mri_->createVirtualRegister(rc);
       vrm.grow();
       CreatedNewVReg = true;
+
+      // The new virtual register should get the same allocation hints as the
+      // old one.
+      std::pair<unsigned, unsigned> Hint = mri_->getRegAllocationHint(Reg);
+      if (Hint.first || Hint.second)
+        mri_->setRegAllocationHint(NewVReg, Hint.first, Hint.second);
     }
 
     if (!TryFold)

Modified: llvm/trunk/test/CodeGen/X86/2008-08-05-SpillerBug.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/2008-08-05-SpillerBug.ll?rev=90163&r1=90162&r2=90163&view=diff

==============================================================================
--- llvm/trunk/test/CodeGen/X86/2008-08-05-SpillerBug.ll (original)
+++ llvm/trunk/test/CodeGen/X86/2008-08-05-SpillerBug.ll Mon Nov 30 16:55:54 2009
@@ -1,4 +1,4 @@
-; RUN: llc < %s -mtriple=i386-apple-darwin -disable-fp-elim -stats |& grep asm-printer | grep 59
+; RUN: llc < %s -mtriple=i386-apple-darwin -disable-fp-elim -stats |& grep asm-printer | grep 58
 ; PR2568
 
 @g_3 = external global i16		; <i16*> [#uses=1]