From ffea00f64925d032da42093be1ce5fd7d8fb2f43 Mon Sep 17 00:00:00 2001
From: James Molloy <james.molloy@arm.com>
Date: Wed, 22 Apr 2015 09:11:38 +0000
Subject: [PATCH] [AArch64] Disable complex GEP optimization by default.

Enough concerns were raised that this optimization is pessimising some code patterns.

The obvious fix, to add a Reassociate run afterwards, causes even more pessimisation in some cases due to fewer complex addressing modes being matched. As there isn't a trivial fix for this, backing this out by default until someone gets a chance to fix the addressing mode matcher.

llvm-svn: 235491
---
 lib/Target/AArch64/AArch64TargetMachine.cpp | 2 +-
 test/CodeGen/AArch64/aarch64-gep-opt.ll     | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/Target/AArch64/AArch64TargetMachine.cpp b/lib/Target/AArch64/AArch64TargetMachine.cpp
index ab28a16515d..a9059ab37f5 100644
--- a/lib/Target/AArch64/AArch64TargetMachine.cpp
+++ b/lib/Target/AArch64/AArch64TargetMachine.cpp
@@ -85,7 +85,7 @@ EnableA53Fix835769("aarch64-fix-cortex-a53-835769", cl::Hidden,
 static cl::opt<bool>
 EnableGEPOpt("aarch64-gep-opt", cl::Hidden,
              cl::desc("Enable optimizations on complex GEPs"),
-             cl::init(true));
+             cl::init(false));
 
 // FIXME: Unify control over GlobalMerge.
 static cl::opt<cl::boolOrDefault>
diff --git a/test/CodeGen/AArch64/aarch64-gep-opt.ll b/test/CodeGen/AArch64/aarch64-gep-opt.ll
index ce6c8a06c64..93e2ff14ac7 100644
--- a/test/CodeGen/AArch64/aarch64-gep-opt.ll
+++ b/test/CodeGen/AArch64/aarch64-gep-opt.ll
@@ -1,6 +1,6 @@
-; RUN: llc -O3 -verify-machineinstrs %s -o - | FileCheck %s
-; RUN: llc -O3 -print-after=codegenprepare -mcpu=cyclone < %s >%t 2>&1 && FileCheck --check-prefix=CHECK-NoAA <%t %s
-; RUN: llc -O3 -print-after=codegenprepare -mcpu=cortex-a53 < %s >%t 2>&1 && FileCheck --check-prefix=CHECK-UseAA <%t %s
+; RUN: llc -O3 -aarch64-gep-opt=true -verify-machineinstrs %s -o - | FileCheck %s
+; RUN: llc -O3 -aarch64-gep-opt=true -print-after=codegenprepare -mcpu=cyclone < %s >%t 2>&1 && FileCheck --check-prefix=CHECK-NoAA <%t %s
+; RUN: llc -O3 -aarch64-gep-opt=true -print-after=codegenprepare -mcpu=cortex-a53 < %s >%t 2>&1 && FileCheck --check-prefix=CHECK-UseAA <%t %s
 target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
 target triple = "aarch64-linux-gnueabi"