[llvm] r270251 - [AArch64] Disable narrow load merge by default

[Jun Bum Lim via llvm-commits]

Author: junbuml
Date: Fri May 20 13:45:49 2016
New Revision: 270251

URL: http://llvm.org/viewvc/llvm-project?rev=270251&view=rev
Log:
[AArch64] Disable narrow load merge by default

Summary:
As this optimization converts two loads into one load with two shift instructions,
it could potentially hurt performance if a loop is arithmetic operation intensive.

Reviewers: t.p.northover, mcrosier, jmolloy

Subscribers: evandro, jmolloy, aemerson, rengolin, mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D20172

Modified:
    llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
    llvm/trunk/test/CodeGen/AArch64/arm64-narrow-ldst-merge.ll

Modified: llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp?rev=270251&r1=270250&r2=270251&view=diff
==============================================================================
--- llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp (original)
+++ llvm/trunk/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp Fri May 20 13:45:49 2016
@@ -52,7 +52,7 @@ static cl::opt<unsigned> UpdateLimit("aa
                                      cl::Hidden);
 
 static cl::opt<bool> EnableNarrowLdMerge("enable-narrow-ld-merge", cl::Hidden,
-                                         cl::init(true),
+                                         cl::init(false),
                                          cl::desc("Enable narrow load merge"));
 
 namespace llvm {

Modified: llvm/trunk/test/CodeGen/AArch64/arm64-narrow-ldst-merge.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/AArch64/arm64-narrow-ldst-merge.ll?rev=270251&r1=270250&r2=270251&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/AArch64/arm64-narrow-ldst-merge.ll (original)
+++ llvm/trunk/test/CodeGen/AArch64/arm64-narrow-ldst-merge.ll Fri May 20 13:45:49 2016
@@ -1,6 +1,6 @@
-; RUN: llc < %s -mtriple aarch64--none-eabi -mcpu=cortex-a57 -verify-machineinstrs | FileCheck %s --check-prefix=CHECK --check-prefix=LE
-; RUN: llc < %s -mtriple aarch64_be--none-eabi -mcpu=cortex-a57 -verify-machineinstrs | FileCheck %s --check-prefix=CHECK --check-prefix=BE
-; RUN: llc < %s -mtriple aarch64--none-eabi -mcpu=kryo -verify-machineinstrs | FileCheck %s --check-prefix=CHECK --check-prefix=LE
+; RUN: llc < %s -mtriple aarch64--none-eabi -mcpu=cortex-a57 -verify-machineinstrs -enable-narrow-ld-merge=true | FileCheck %s --check-prefix=CHECK --check-prefix=LE
+; RUN: llc < %s -mtriple aarch64_be--none-eabi -mcpu=cortex-a57 -verify-machineinstrs -enable-narrow-ld-merge=true | FileCheck %s --check-prefix=CHECK --check-prefix=BE
+; RUN: llc < %s -mtriple aarch64--none-eabi -mcpu=kryo -verify-machineinstrs -enable-narrow-ld-merge=true | FileCheck %s --check-prefix=CHECK --check-prefix=LE
 
 ; CHECK-LABEL: Ldrh_merge
 ; CHECK-NOT: ldrh