Revert r338354 "[ARM] Revert r337821"

Disable ARMCodeGenPrepare by default again. It is causing verifier
failues in V8 that look like:

  Duplicate integer as switch case
  switch i32 %trunc, label %if.end13 [
    i32 0, label %cleanup36
    i32 0, label %if.then8
  ], !dbg !4981
  i32 0
  fatal error: error in backend: Broken function found, compilation aborted!

I will continue reducing the test case and send it along.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338452 91177308-0d34-0410-b5e6-96231b3b80d8

Author: rnk

lib/Target/ARM/ARMCodeGenPrepare.cpp

@@ -42,7 +42,7 @@
 using namespace llvm;
 
 static cl::opt<bool>
-DisableCGP("arm-disable-cgp", cl::Hidden, cl::init(false),
+DisableCGP("arm-disable-cgp", cl::Hidden, cl::init(true),
            cl::desc("Disable ARM specific CodeGenPrepare pass"));
 
 static cl::opt<bool>

test/CodeGen/ARM/arm-cgp-icmps.ll

@@ -1,6 +1,6 @@
-; RUN: llc -mtriple=thumbv8.main -mcpu=cortex-m33 %s -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-NODSP
-; RUN: llc -mtriple=thumbv7em %s -arm-enable-scalar-dsp=true -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP
-; RUN: llc -mtriple=thumbv8 %s -arm-enable-scalar-dsp=true -arm-enable-scalar-dsp-imms=true -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP-IMM
+; RUN: llc -mtriple=thumbv8.main -mcpu=cortex-m33 %s -arm-disable-cgp=false -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-NODSP
+; RUN: llc -mtriple=thumbv7em %s -arm-disable-cgp=false -arm-enable-scalar-dsp=true -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP
+; RUN: llc -mtriple=thumbv8 %s -arm-disable-cgp=false -arm-enable-scalar-dsp=true -arm-enable-scalar-dsp-imms=true -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP-IMM
 
 ; CHECK-COMMON-LABEL: test_ult_254_inc_imm:
 ; CHECK-DSP:        adds    r0, #1

test/CodeGen/ARM/arm-cgp-phis-calls-ret.ll

@@ -1,7 +1,7 @@
-; RUN: llc -mtriple=thumbv7m %s -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-NODSP
-; RUN: llc -mtriple=thumbv8m.main %s -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-NODSP
-; RUN: llc -mtriple=thumbv8m.main -arm-enable-scalar-dsp=true -mcpu=cortex-m33 %s -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP
-; RUN: llc -mtriple=thumbv7em %s -arm-enable-scalar-dsp=true -arm-enable-scalar-dsp-imms=true -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP-IMM
+; RUN: llc -mtriple=thumbv7m -arm-disable-cgp=false %s -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-NODSP
+; RUN: llc -mtriple=thumbv8m.main -arm-disable-cgp=false %s -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-NODSP
+; RUN: llc -mtriple=thumbv8m.main -arm-disable-cgp=false -arm-enable-scalar-dsp=true -mcpu=cortex-m33 %s -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP
+; RUN: llc -mtriple=thumbv7em %s -arm-disable-cgp=false -arm-enable-scalar-dsp=true -arm-enable-scalar-dsp-imms=true -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP-IMM
 
 ; Test that ARMCodeGenPrepare can handle:
 ; - loops

test/CodeGen/ARM/arm-cgp-signed.ll

@@ -1,7 +1,7 @@
-; RUN: llc -mtriple=thumbv7m %s -o - | FileCheck %s
-; RUN: llc -mtriple=thumbv8m.main %s -o - | FileCheck %s
-; RUN: llc -mtriple=thumbv7 %s -o - | FileCheck %s
-; RUN: llc -mtriple=armv8 %s -o - | FileCheck %s
+; RUN: llc -mtriple=thumbv7m -arm-disable-cgp=false %s -o - | FileCheck %s
+; RUN: llc -mtriple=thumbv8m.main -arm-disable-cgp=false %s -o - | FileCheck %s
+; RUN: llc -mtriple=thumbv7 %s -arm-disable-cgp=false -o - | FileCheck %s
+; RUN: llc -mtriple=armv8 %s -arm-disable-cgp=false -o - | FileCheck %s
 
 ; Test to check that ARMCodeGenPrepare doesn't optimised away sign extends.
 ; CHECK-LABEL: test_signed_load: