[llvm-commits] [llvm] r61179 - /llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp

[Dan Gohman]

Author: djg
Date: Wed Dec 17 19:05:09 2008
New Revision: 61179

URL: http://llvm.org/viewvc/llvm-project?rev=61179&view=rev
Log:
Mark the x86 fp stack registers as "reserved". This tells LiveVariables
and the RegisterScavenger not to expect traditional liveness 
techniques are applicable to these registers, since we don't fully
modify the effects of push and pop after stackification.

Modified:
    llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp

Modified: llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp?rev=61179&r1=61178&r2=61179&view=diff

==============================================================================
--- llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86RegisterInfo.cpp Wed Dec 17 19:05:09 2008
@@ -263,16 +263,30 @@
 
 BitVector X86RegisterInfo::getReservedRegs(const MachineFunction &MF) const {
   BitVector Reserved(getNumRegs());
+  // Set the stack-pointer register and its aliases as reserved.
   Reserved.set(X86::RSP);
   Reserved.set(X86::ESP);
   Reserved.set(X86::SP);
   Reserved.set(X86::SPL);
+  // Set the frame-pointer register and its aliases as reserved if needed.
   if (hasFP(MF)) {
     Reserved.set(X86::RBP);
     Reserved.set(X86::EBP);
     Reserved.set(X86::BP);
     Reserved.set(X86::BPL);
   }
+  // Mark the x87 stack registers as reserved, since they don't
+  // behave normally with respect to liveness. We don't fully
+  // model the effects of x87 stack pushes and pops after
+  // stackification.
+  Reserved.set(X86::ST0);
+  Reserved.set(X86::ST1);
+  Reserved.set(X86::ST2);
+  Reserved.set(X86::ST3);
+  Reserved.set(X86::ST4);
+  Reserved.set(X86::ST5);
+  Reserved.set(X86::ST6);
+  Reserved.set(X86::ST7);
   return Reserved;
 }