[PATCH] D14778: [PPC64] Enable shrink wrapping for PPC64 LE.

[Kit Barton via llvm-commits]

kbarton created this revision.
kbarton added reviewers: hfinkel, nemanjai, seurer, qcolombet.
kbarton added a subscriber: llvm-commits.

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. 

http://reviews.llvm.org/D14778

Files:
  lib/Target/PowerPC/PPCFrameLowering.cpp
  test/CodeGen/PowerPC/ppc-shrink-wrapping.ll

Index: test/CodeGen/PowerPC/ppc-shrink-wrapping.ll
===================================================================
--- test/CodeGen/PowerPC/ppc-shrink-wrapping.ll
+++ test/CodeGen/PowerPC/ppc-shrink-wrapping.ll
@@ -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.
Index: lib/Target/PowerPC/PPCFrameLowering.cpp
===================================================================
--- lib/Target/PowerPC/PPCFrameLowering.cpp
+++ lib/Target/PowerPC/PPCFrameLowering.cpp
@@ -573,10 +573,18 @@
   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 @@
 }
 
 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());
 }


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D14778.40517.patch
Type: text/x-patch
Size: 1950 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20151118/fce71780/attachment.bin>