[ARM] Temporarily disable globals promotion to constant pools to prev…

…ent 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

llvm-svn: 303679

llvm/lib/Target/ARM/ARMISelLowering.cpp

@@ -127,7 +127,7 @@ static cl::opt<bool> EnableConstpoolPromotion(
     "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"),

llvm/test/CodeGen/ARM/constantpool-promote-dbg.ll

@@ -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"

llvm/test/CodeGen/ARM/constantpool-promote-ldrh.ll

@@ -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"
 

llvm/test/CodeGen/ARM/constantpool-promote.ll

@@ -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