[PATCH] D13467: [mips] Handle undef when extracting subregs from FP64 registers.

[Daniel Sanders via llvm-commits]

dsanders created this revision.
dsanders added a reviewer: vkalintiris.
dsanders added subscribers: petarj, zoran.jovanovic, llvm-commits.

This removes unnecessary instructions when extracting from an undefined register
and also fixes a crash for O32 when passing undef to a double argument in
held in integer registers.

http://reviews.llvm.org/D13467

Files:
  lib/Target/Mips/MipsSEFrameLowering.cpp
  test/CodeGen/Mips/llvm-ir/call.ll

Index: test/CodeGen/Mips/llvm-ir/call.ll
===================================================================
--- test/CodeGen/Mips/llvm-ir/call.ll
+++ test/CodeGen/Mips/llvm-ir/call.ll
@@ -6,6 +6,7 @@
 ; RUN: llc -march=mips   -mcpu=mips32r3 -enable-mips-tail-calls < %s | FileCheck %s -check-prefix=ALL -check-prefix=O32
 ; RUN: llc -march=mips   -mcpu=mips32r5 -enable-mips-tail-calls < %s | FileCheck %s -check-prefix=ALL -check-prefix=O32
 ; RUN: llc -march=mips   -mcpu=mips32r6 -enable-mips-tail-calls < %s | FileCheck %s -check-prefix=ALL -check-prefix=O32
+; RUN: llc -march=mips   -mcpu=mips32r6 -mattr=+fp64,+nooddspreg -enable-mips-tail-calls < %s | FileCheck %s -check-prefix=ALL -check-prefix=O32
 ; RUN: llc -march=mips64 -mcpu=mips4    -enable-mips-tail-calls < %s | FileCheck %s -check-prefix=ALL -check-prefix=N64
 ; RUN: llc -march=mips64 -mcpu=mips64   -enable-mips-tail-calls < %s | FileCheck %s -check-prefix=ALL -check-prefix=N64
 ; RUN: llc -march=mips64 -mcpu=mips64r2 -enable-mips-tail-calls < %s | FileCheck %s -check-prefix=ALL -check-prefix=N64
@@ -168,3 +169,16 @@
   %1 = tail call float %addr()
   ret float %1
 }
+
+; Check that passing undef as a double value doesn't cause machine code errors
+; for FP64.
+declare hidden void @undef_double(i32 %this, double %volume) unnamed_addr align 2
+
+define hidden void @thunk_undef_double(i32 %this, double %volume) unnamed_addr align 2 {
+; ALL-LABEL: thunk_undef_double:
+; O32: # implicit-def: A2
+; O32: # implicit-def: A3
+; ALL: jr $25
+  tail call void @undef_double(i32 undef, double undef) #8
+  ret void
+}
Index: lib/Target/Mips/MipsSEFrameLowering.cpp
===================================================================
--- lib/Target/Mips/MipsSEFrameLowering.cpp
+++ lib/Target/Mips/MipsSEFrameLowering.cpp
@@ -319,6 +319,12 @@
 bool ExpandPseudo::expandExtractElementF64(MachineBasicBlock &MBB,
                                            MachineBasicBlock::iterator I,
                                            bool FP64) const {
+  if (I->getOperand(1).isUndef() || I->getOperand(2).isUndef()) {
+    unsigned DstReg = I->getOperand(0).getReg();
+    BuildMI(MBB, I, DebugLoc(), TII.get(Mips::IMPLICIT_DEF), DstReg);
+    return true;
+  }
+
   // For fpxx and when mfhc1 is not available, use:
   //   spill + reload via ldc1
   //


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