[AArch64] Use 16 bytes as preferred function alignment on Cortex-A72.

Summary:
This change gives a 0.34% speed on execution time, a 0.61% improvement
in benchmark scores and a 0.57% increase in binary size on a Cortex-A72.
These numbers are the geomean results on a wide range of benchmarks from
the test-suite, SPEC2000, SPEC2006 and a range of proprietary suites.

The software optimization guide for the Cortex-A72 recommends 16 byte
branch alignment.

Reviewers: t.p.northover, kristof.beyls, rengolin, sbaranga, mcrosier, javed.absar

Reviewed By: kristof.beyls

Subscribers: llvm-commits, aemerson

Differential Revision: https://reviews.llvm.org/D34961

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@307380 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AArch64/AArch64Subtarget.cpp b/lib/Target/AArch64/AArch64Subtarget.cpp
index a9a9d5c..df620cc 100644 (file)
--- a/lib/Target/AArch64/AArch64Subtarget.cpp
+++ b/lib/Target/AArch64/AArch64Subtarget.cpp
@@ -130,7 +130,9 @@ void AArch64Subtarget::initializeProperties() {
     break;
   case CortexA35: break;
   case CortexA53: break;
-  case CortexA72: break;
+  case CortexA72:
+    PrefFunctionAlignment = 4;
+    break;
   case CortexA73: break;
   case Others: break;
   }

diff --git a/test/CodeGen/AArch64/preferred-function-alignment.ll b/test/CodeGen/AArch64/preferred-function-alignment.ll
index 0a86f11..3b3af88 100644 (file)
--- a/test/CodeGen/AArch64/preferred-function-alignment.ll
+++ b/test/CodeGen/AArch64/preferred-function-alignment.ll
@@ -2,7 +2,6 @@
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=cortex-a35 < %s | FileCheck --check-prefix=ALIGN2 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=cortex-a53 < %s | FileCheck --check-prefix=ALIGN2 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=cortex-a57 < %s | FileCheck --check-prefix=ALIGN2 %s
-; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=cortex-a72 < %s | FileCheck --check-prefix=ALIGN2 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=cortex-a73 < %s | FileCheck --check-prefix=ALIGN2 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=cyclone < %s | FileCheck --check-prefix=ALIGN2 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=falkor < %s | FileCheck --check-prefix=ALIGN2 %s
@@ -12,6 +11,7 @@
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=thunderxt83 < %s | FileCheck --check-prefix=ALIGN3 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=thunderxt88 < %s | FileCheck --check-prefix=ALIGN3 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=thunderx2t99 < %s | FileCheck --check-prefix=ALIGN3 %s
+; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=cortex-a72 < %s | FileCheck --check-prefix=ALIGN4 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=exynos-m1 < %s | FileCheck --check-prefix=ALIGN4 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=exynos-m2 < %s | FileCheck --check-prefix=ALIGN4 %s
 ; RUN: llc -mtriple=aarch64-unknown-linux -mcpu=exynos-m3 < %s | FileCheck --check-prefix=ALIGN4 %s