[llvm] r179457 - Spill and restore PPC CR registers using the FP when we have one

[Hal Finkel]

Author: hfinkel
Date: Sat Apr 13 03:09:20 2013
New Revision: 179457

URL: http://llvm.org/viewvc/llvm-project?rev=179457&view=rev
Log:
Spill and restore PPC CR registers using the FP when we have one

For functions that need to spill CRs, and have dynamic stack allocations, the
value of the SP during the restore is not what it was during the save, and so
we need to use the FP in these cases (as for all of the other spills and
restores, but the CR restore has a special code path because its reserved slot,
like the link register, is specified directly relative to the adjusted SP).

Modified:
    llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp
    llvm/trunk/test/CodeGen/PowerPC/crsave.ll

Modified: llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp?rev=179457&r1=179456&r2=179457&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp Sat Apr 13 03:09:20 2013
@@ -1141,12 +1141,14 @@ PPCFrameLowering::spillCalleeSavedRegist
       // save slot via GPR12 (available in the prolog for 32- and 64-bit).
       if (Subtarget.isPPC64()) {
 	// 64-bit:  SP+8
+        bool is31 = needsFP(*MF);
+        unsigned FP8Reg = is31 ? PPC::X31 : PPC::X1;
 	MBB.insert(MI, BuildMI(*MF, DL, TII.get(PPC::MFCR8), PPC::X12));
 	MBB.insert(MI, BuildMI(*MF, DL, TII.get(PPC::STW8))
 			       .addReg(PPC::X12,
 				       getKillRegState(true))
 			       .addImm(8)
-			       .addReg(PPC::X1));
+			       .addReg(FP8Reg));
       } else {
 	// 32-bit:  FP-relative.  Note that we made sure CR2-CR4 all have
 	// the same frame index in PPCRegisterInfo::hasReservedSpillSlot.
@@ -1170,7 +1172,8 @@ PPCFrameLowering::spillCalleeSavedRegist
 }
 
 static void
-restoreCRs(bool isPPC64, bool CR2Spilled, bool CR3Spilled, bool CR4Spilled,
+restoreCRs(bool isPPC64, bool is31,
+           bool CR2Spilled, bool CR3Spilled, bool CR4Spilled,
 	   MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
 	   const std::vector<CalleeSavedInfo> &CSI, unsigned CSIIndex) {
 
@@ -1182,9 +1185,10 @@ restoreCRs(bool isPPC64, bool CR2Spilled
 
   if (isPPC64) {
     // 64-bit:  SP+8
+    unsigned FP8Reg = is31 ? PPC::X31 : PPC::X1;
     MBB.insert(MI, BuildMI(*MF, DL, TII.get(PPC::LWZ8), PPC::X12)
 	       .addImm(8)
-	       .addReg(PPC::X1));
+	       .addReg(FP8Reg));
     RestoreOp = PPC::MTCRF8;
     MoveReg = PPC::X12;
   } else {
@@ -1297,7 +1301,9 @@ PPCFrameLowering::restoreCalleeSavedRegi
       // least one CR register, restore all spilled CRs together.
       if ((CR2Spilled || CR3Spilled || CR4Spilled)
 	  && !(PPC::CR2 <= Reg && Reg <= PPC::CR4)) {
-	restoreCRs(Subtarget.isPPC64(), CR2Spilled, CR3Spilled, CR4Spilled,
+        bool is31 = needsFP(*MF);
+        restoreCRs(Subtarget.isPPC64(), is31,
+                   CR2Spilled, CR3Spilled, CR4Spilled,
 		   MBB, I, CSI, CSIIndex);
 	CR2Spilled = CR3Spilled = CR4Spilled = false;
       }
@@ -1320,9 +1326,11 @@ PPCFrameLowering::restoreCalleeSavedRegi
   }
 
   // If we haven't yet spilled the CRs, do so now.
-  if (CR2Spilled || CR3Spilled || CR4Spilled)
-    restoreCRs(Subtarget.isPPC64(), CR2Spilled, CR3Spilled, CR4Spilled,
+  if (CR2Spilled || CR3Spilled || CR4Spilled) {
+    bool is31 = needsFP(*MF); 
+    restoreCRs(Subtarget.isPPC64(), is31, CR2Spilled, CR3Spilled, CR4Spilled,
 	       MBB, I, CSI, CSIIndex);
+  }
 
   return true;
 }

Modified: llvm/trunk/test/CodeGen/PowerPC/crsave.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/crsave.ll?rev=179457&r1=179456&r2=179457&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/PowerPC/crsave.ll (original)
+++ llvm/trunk/test/CodeGen/PowerPC/crsave.ll Sat Apr 13 03:09:20 2013
@@ -1,5 +1,6 @@
 ; RUN: llc -O0 -disable-fp-elim -mtriple=powerpc-unknown-linux-gnu < %s | FileCheck %s -check-prefix=PPC32
-; RUN: llc -O0 -disable-fp-elim -mtriple=powerpc64-unknown-linux-gnu < %s | FileCheck %s -check-prefix=PPC64
+; RUN: llc -O0 -disable-fp-elim -mtriple=powerpc64-unknown-linux-gnu < %s | FileCheck %s -check-prefix=PPC64-FP
+; RUN: llc -O0 -mtriple=powerpc64-unknown-linux-gnu < %s | FileCheck %s -check-prefix=PPC64
 
 declare void @foo()
 
@@ -23,6 +24,11 @@ entry:
 ; PPC64: lwz 12, 8(1)
 ; PPC64-NEXT: mtcrf 32, 12
 
+; PPC64-FP: mfcr 12
+; PPC64-FP-NEXT: stw 12, 8(31)
+; PPC64-FP: lwz 12, 8(31)
+; PPC64-FP-NEXT: mtcrf 32, 12
+
 define i32 @test_cr234() nounwind {
 entry:
   %ret = alloca i32, align 4
@@ -47,3 +53,10 @@ entry:
 ; PPC64-NEXT: mtcrf 16, 12
 ; PPC64-NEXT: mtcrf 8, 12
 
+; PPC64-FP: mfcr 12
+; PPC64-FP-NEXT: stw 12, 8(31)
+; PPC64-FP: lwz 12, 8(31)
+; PPC64-FP-NEXT: mtcrf 32, 12
+; PPC64-FP-NEXT: mtcrf 16, 12
+; PPC64-FP-NEXT: mtcrf 8, 12
+