[llvm] r303679 - [ARM] Temporarily disable globals promotion to constant pools to prevent miscompilation

[Oleg Ranevskyy via llvm-commits]

Author: oleg
Date: Tue May 23 14:38:37 2017
New Revision: 303679

URL: http://llvm.org/viewvc/llvm-project?rev=303679&view=rev
Log:
[ARM] Temporarily disable globals promotion to constant pools to prevent miscompilation

Summary:
A temporary workaround for PR32780 - rematerialized instructions accessing the same promoted global through different constant pool entries.

The patch turns off the globals promotion optimization leaving all its code in place, so that it can be easily turned on once PR32780 is fixed.

Since this is a miscompilation issue causing generation of misbehaving code, and the problem is very subtle, the patch might be valuable enough to get into 4.0.1.

Reviewers: efriedma, jmolloy

Reviewed By: efriedma

Subscribers: aemerson, javed.absar, llvm-commits, rengolin, asl, tstellar

Differential Revision: https://reviews.llvm.org/D33446

Modified:
    llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
    llvm/trunk/test/CodeGen/ARM/constantpool-promote-dbg.ll
    llvm/trunk/test/CodeGen/ARM/constantpool-promote-ldrh.ll
    llvm/trunk/test/CodeGen/ARM/constantpool-promote.ll

Modified: llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp?rev=303679&r1=303678&r2=303679&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelLowering.cpp Tue May 23 14:38:37 2017
@@ -127,7 +127,7 @@ static cl::opt<bool> EnableConstpoolProm
     "arm-promote-constant", cl::Hidden,
     cl::desc("Enable / disable promotion of unnamed_addr constants into "
              "constant pools"),
-    cl::init(true));
+    cl::init(false)); // FIXME: set to true by default once PR32780 is fixed
 static cl::opt<unsigned> ConstpoolPromotionMaxSize(
     "arm-promote-constant-max-size", cl::Hidden,
     cl::desc("Maximum size of constant to promote into a constant pool"),

Modified: llvm/trunk/test/CodeGen/ARM/constantpool-promote-dbg.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/constantpool-promote-dbg.ll?rev=303679&r1=303678&r2=303679&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/constantpool-promote-dbg.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/constantpool-promote-dbg.ll Tue May 23 14:38:37 2017
@@ -1,4 +1,4 @@
-; RUN: llc -relocation-model=static < %s | FileCheck %s
+; RUN: llc -relocation-model=static -arm-promote-constant < %s | FileCheck %s
 
 target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
 target triple = "thumbv7m--linux-gnu"

Modified: llvm/trunk/test/CodeGen/ARM/constantpool-promote-ldrh.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/constantpool-promote-ldrh.ll?rev=303679&r1=303678&r2=303679&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/constantpool-promote-ldrh.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/constantpool-promote-ldrh.ll Tue May 23 14:38:37 2017
@@ -1,5 +1,5 @@
-; RUN: llc < %s -O0 -fast-isel=false | FileCheck %s
-; RUN: llc < %s -O0 -fast-isel=false -filetype=obj
+; RUN: llc < %s -O0 -fast-isel=false -arm-promote-constant | FileCheck %s
+; RUN: llc < %s -O0 -fast-isel=false -filetype=obj -arm-promote-constant
 target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
 target triple = "thumbv6m-arm-linux-gnueabi"
 

Modified: llvm/trunk/test/CodeGen/ARM/constantpool-promote.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/constantpool-promote.ll?rev=303679&r1=303678&r2=303679&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/constantpool-promote.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/constantpool-promote.ll Tue May 23 14:38:37 2017
@@ -1,15 +1,15 @@
-; RUN: llc -mtriple armv7--linux-gnueabihf -relocation-model=static < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7ARM
-; RUN: llc -mtriple armv7--linux-gnueabihf -relocation-model=pic < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7ARM
-; RUN: llc -mtriple armv7--linux-gnueabihf -relocation-model=ropi < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7ARM
-; RUN: llc -mtriple armv7--linux-gnueabihf -relocation-model=rwpi < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7ARM
-; RUN: llc -mtriple thumbv7--linux-gnueabihf -relocation-model=static < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7THUMB
-; RUN: llc -mtriple thumbv7--linux-gnueabihf -relocation-model=pic < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7THUMB
-; RUN: llc -mtriple thumbv7--linux-gnueabihf -relocation-model=ropi < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7THUMB
-; RUN: llc -mtriple thumbv7--linux-gnueabihf -relocation-model=rwpi < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7THUMB
-; RUN: llc -mtriple thumbv6m--linux-gnueabihf -relocation-model=static < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V6M
-; RUN: llc -mtriple thumbv6m--linux-gnueabihf -relocation-model=pic < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V6M
-; RUN: llc -mtriple thumbv6m--linux-gnueabihf -relocation-model=ropi < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V6M
-; RUN: llc -mtriple thumbv6m--linux-gnueabihf -relocation-model=rwpi < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V6M
+; RUN: llc -mtriple armv7--linux-gnueabihf -relocation-model=static -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7ARM
+; RUN: llc -mtriple armv7--linux-gnueabihf -relocation-model=pic -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7ARM
+; RUN: llc -mtriple armv7--linux-gnueabihf -relocation-model=ropi -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7ARM
+; RUN: llc -mtriple armv7--linux-gnueabihf -relocation-model=rwpi -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7ARM
+; RUN: llc -mtriple thumbv7--linux-gnueabihf -relocation-model=static -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7THUMB
+; RUN: llc -mtriple thumbv7--linux-gnueabihf -relocation-model=pic -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7THUMB
+; RUN: llc -mtriple thumbv7--linux-gnueabihf -relocation-model=ropi -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7THUMB
+; RUN: llc -mtriple thumbv7--linux-gnueabihf -relocation-model=rwpi -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V7,CHECK-V7THUMB
+; RUN: llc -mtriple thumbv6m--linux-gnueabihf -relocation-model=static -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V6M
+; RUN: llc -mtriple thumbv6m--linux-gnueabihf -relocation-model=pic -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V6M
+; RUN: llc -mtriple thumbv6m--linux-gnueabihf -relocation-model=ropi -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V6M
+; RUN: llc -mtriple thumbv6m--linux-gnueabihf -relocation-model=rwpi -arm-promote-constant < %s | FileCheck %s --check-prefixes=CHECK,CHECK-V6M
 
 @.str = private unnamed_addr constant [2 x i8] c"s\00", align 1
 @.str1 = private unnamed_addr constant [69 x i8] c"this string is far too long to fit in a literal pool by far and away\00", align 1