[llvm] r254314 - Enable shrink wrapping for PPC64

[Kit Barton via llvm-commits]

Author: kbarton
Date: Mon Nov 30 12:59:41 2015
New Revision: 254314

URL: http://llvm.org/viewvc/llvm-project?rev=254314&view=rev
Log:
Enable shrink wrapping for PPC64

Re-enable shrink wrapping for PPC64 Little Endian.

One minor modification to PPCFrameLowering::findScratchRegister was necessary to handle fall-thru blocks (blocks with no terminator) correctly.

Tested with all LLVM test, clang tests, and the self-hosting build, with no problems found.

PHabricator: http://reviews.llvm.org/D14778

Modified:
    llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp
    llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll

Modified: llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp?rev=254314&r1=254313&r2=254314&view=diff
==============================================================================
--- llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp (original)
+++ llvm/trunk/lib/Target/PowerPC/PPCFrameLowering.cpp Mon Nov 30 12:59:41 2015
@@ -573,10 +573,18 @@ bool PPCFrameLowering::findScratchRegist
   RS.initRegState();
   RS.enterBasicBlock(MBB);
 
-  // The scratch register will be used at the end of the block, so must consider
-  // all registers used within the block
-  if (UseAtEnd && MBB->begin() != MBB->getFirstTerminator())
-    RS.forward(MBB->getFirstTerminator());
+  if (UseAtEnd && !MBB->empty()) {
+    // The scratch register will be used at the end of the block, so must consider
+    // all registers used within the block
+
+    MachineBasicBlock::iterator MBBI = MBB->getFirstTerminator();
+    // If no terminator, back iterator up to previous instruction.
+    if (MBBI == MBB->end())
+      MBBI = std::prev(MBBI);
+
+    if (MBBI != MBB->begin())
+      RS.forward(MBBI);
+  }
   
   if (!RS.isRegUsed(R0)) 
     return true;
@@ -1768,6 +1776,6 @@ PPCFrameLowering::restoreCalleeSavedRegi
 }
 
 bool PPCFrameLowering::enableShrinkWrapping(const MachineFunction &MF) const {
-  // FIXME: Enable this for non-Darwin PPC64 once it is confirmed working.
-  return false;
+  return (MF.getSubtarget<PPCSubtarget>().isSVR4ABI() &&
+          MF.getSubtarget<PPCSubtarget>().isPPC64());
 }

Modified: llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll?rev=254314&r1=254313&r2=254314&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll (original)
+++ llvm/trunk/test/CodeGen/PowerPC/ppc-shrink-wrapping.ll Mon Nov 30 12:59:41 2015
@@ -1,6 +1,5 @@
 ; RUN: llc -mtriple=powerpc64le-unknown-linux-gnu -mcpu=pwr8 %s -o - | FileCheck %s --check-prefix=CHECK --check-prefix=ENABLE
 ; RUN: llc -mtriple=powerpc64le-unknown-linux-gnu %s -o - -enable-shrink-wrap=false |  FileCheck %s --check-prefix=CHECK --check-prefix=DISABLE
-; XFAIL: *
 ;
 ; Note: Lots of tests use inline asm instead of regular calls.
 ; This allows to have a better control on what the allocation will do.