[WebAssembly] Rematerialize constants rather than hold them live in registers.

Teach the register stackifier to rematerialize constants that have multiple
uses instead of leaving them in registers. In the WebAssembly encoding, it's
the same code size to materialize most constants as it is to read a value
from a register.

llvm-svn: 258142

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.h b/llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.h
index 5ddd9b36f24..bf0c1dc6c95 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.h
@@ -34,6 +34,9 @@ public:
 
   const WebAssemblyRegisterInfo &getRegisterInfo() const { return RI; }
 
+  bool isReallyTriviallyReMaterializable(const MachineInstr *MI,
+                                         AliasAnalysis *AA) const override;
+
   void copyPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
                    DebugLoc DL, unsigned DestReg, unsigned SrcReg,
                    bool KillSrc) const override;