[PATCH] D14360: [AArch64] Enable shrink-wrapping by default

[Quentin Colombet via llvm-commits]

qcolombet created this revision.
qcolombet added reviewers: t.p.northover, mcrosier.
qcolombet added a subscriber: llvm-commits.
qcolombet set the repository for this revision to rL LLVM.
Herald added subscribers: rengolin, aemerson.

Hi,

This is the AArch64 version of enable shrink-wrapping by default, but since copy/paste are cheap, here is a longer description :).

This patch enables shrink-wrapping by default for AArch64.
I have tested shrink-wrapping and no correctness problems came out or runtime regressions.
Although the gain may be small, the code looks nicer with shrink-wrapping enabled and the performance could just be better.

For the record shrink-wrapping was introduced after this review:
http://reviews.llvm.org/D9210

More information on Shrink-Wrapping:
http://lists.llvm.org/pipermail/llvm-dev/2015-May/085220.html

OK to commit?

Thanks,
-Quentin

Repository:
  rL LLVM

http://reviews.llvm.org/D14360

Files:
  lib/Target/AArch64/AArch64FrameLowering.h
  test/CodeGen/AArch64/aarch64-dynamic-stack-layout.ll

Index: lib/Target/AArch64/AArch64FrameLowering.h
===================================================================
--- lib/Target/AArch64/AArch64FrameLowering.h
+++ lib/Target/AArch64/AArch64FrameLowering.h
@@ -60,6 +60,11 @@
 
   void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs,
                             RegScavenger *RS) const override;
+
+  /// Returns true if the target will correctly handle shrink wrapping.
+  bool enableShrinkWrapping(const MachineFunction &MF) const override {
+    return true;
+  }
 };
 
 } // End llvm namespace
Index: test/CodeGen/AArch64/aarch64-dynamic-stack-layout.ll
===================================================================
--- test/CodeGen/AArch64/aarch64-dynamic-stack-layout.ll
+++ test/CodeGen/AArch64/aarch64-dynamic-stack-layout.ll
@@ -522,10 +522,10 @@
 
 ; CHECK-LABEL: realign_conditional2
 ; Extra realignment in the prologue (performance issue).
+; CHECK:  tbz  {{.*}} .[[LABEL:.*]]
 ; CHECK:  sub  x9, sp, #32            // =32
 ; CHECK:  and  sp, x9, #0xffffffffffffffe0
 ; CHECK:  mov   x19, sp
-; CHECK:  tbz  {{.*}} .[[LABEL:.*]]
 ; Stack is realigned in a non-entry BB.
 ; CHECK:  sub  [[REG:x[01-9]+]], sp, #64
 ; CHECK:  and  sp, [[REG]], #0xffffffffffffffe0


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D14360.39292.patch
Type: text/x-patch
Size: 1249 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20151105/2e827f19/attachment.bin>