[llvm] r304906 - [mips] do not use FastISel when -mxgot is present

[Petar Jovanovic via llvm-commits]

Author: petarj
Date: Wed Jun  7 07:59:53 2017
New Revision: 304906

URL: http://llvm.org/viewvc/llvm-project?rev=304906&view=rev
Log:
[mips] do not use FastISel when -mxgot is present

The clang compiler by default uses FastISel when invoked with -O0, which
is also the default. In that case, passing of -mxgot does not get honored,
i.e. the code path that is to deal with large got is not taken.
Clang produces same output regardless of -mxgot being present or not.
This change checks whether -mxgot is passed as an option, and turns off
FastISel if it is.

Patch by Stefan Maksimovic.

Differential Revision: https://reviews.llvm.org/D33593

Modified:
    llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp
    llvm/trunk/test/CodeGen/Mips/biggot.ll

Modified: llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp?rev=304906&r1=304905&r2=304906&view=diff
==============================================================================
--- llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/Mips/MipsISelLowering.cpp Wed Jun  7 07:59:53 2017
@@ -470,8 +470,9 @@ MipsTargetLowering::createFastISel(Funct
                      !Subtarget.hasMips32r6() && !Subtarget.inMips16Mode() &&
                      !Subtarget.inMicroMipsMode();
 
-  // Disable if we don't generate PIC or the ABI isn't O32.
-  if (!TM.isPositionIndependent() || !TM.getABI().IsO32())
+  // Disable if either of the following is true:
+  // We do not generate PIC, the ABI is not O32, LargeGOT is being used.
+  if (!TM.isPositionIndependent() || !TM.getABI().IsO32() || LargeGOT)
     UseFastISel = false;
 
   return UseFastISel ? Mips::createFastISel(funcInfo, libInfo) : nullptr;

Modified: llvm/trunk/test/CodeGen/Mips/biggot.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Mips/biggot.ll?rev=304906&r1=304905&r2=304906&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Mips/biggot.ll (original)
+++ llvm/trunk/test/CodeGen/Mips/biggot.ll Wed Jun  7 07:59:53 2017
@@ -1,6 +1,9 @@
 ; RUN: llc -march=mipsel -mxgot -relocation-model=pic < %s | FileCheck %s -check-prefix=O32
 ; RUN: llc -march=mips64el -mcpu=mips64r2 -mxgot -relocation-model=pic < %s | \
 ; RUN: FileCheck %s -check-prefix=N64
+; RUN: llc -march=mipsel -mxgot -relocation-model=pic -fast-isel < %s | FileCheck %s -check-prefix=O32
+; RUN: llc -march=mips64el -mcpu=mips64r2 -mxgot -relocation-model=pic -fast-isel < %s | \
+; RUN: FileCheck %s -check-prefix=N64
 
 @v0 = external global i32