[llvm] r178959 - Add a comment to TargetInstrInfo about FoldImmediate
Hal Finkel
hfinkel at anl.gov
Sat Apr 6 12:30:21 PDT 2013
Author: hfinkel
Date: Sat Apr 6 14:30:20 2013
New Revision: 178959
URL: http://llvm.org/viewvc/llvm-project?rev=178959&view=rev
Log:
Add a comment to TargetInstrInfo about FoldImmediate
This comment documents the current behavior of the ARM implementation of this
callback, and also the soon-to-be-committed PPC version.
Modified:
llvm/trunk/include/llvm/Target/TargetInstrInfo.h
Modified: llvm/trunk/include/llvm/Target/TargetInstrInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetInstrInfo.h?rev=178959&r1=178958&r2=178959&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetInstrInfo.h (original)
+++ llvm/trunk/include/llvm/Target/TargetInstrInfo.h Sat Apr 6 14:30:20 2013
@@ -774,6 +774,10 @@ public:
/// FoldImmediate - 'Reg' is known to be defined by a move immediate
/// instruction, try to fold the immediate into the use instruction.
+ /// If MRI->hasOneNonDBGUse(Reg) is true, and this function returns true,
+ /// then the caller may assume that DefMI has been erased from its parent
+ /// block. The caller may assume that it will not be erased by this
+ /// function otherwise.
virtual bool FoldImmediate(MachineInstr *UseMI, MachineInstr *DefMI,
unsigned Reg, MachineRegisterInfo *MRI) const {
return false;
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