[WebAssembly] Fix WebAssembly register numbering for registers added late.

If virtual registers are created late, mappings to WebAssembly
registers need to be added explicitly. This patch adds a function
to do so and teaches WebAssemblyPeephole to use it. This fixes
an out-of-bounds access on the WARegs vector.

llvm-svn: 254094

2 files changed, 9 insertions, 0 deletions

diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
index 9c23412b3cc..4760f0d576e 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyMachineFunctionInfo.h
@@ -63,11 +63,19 @@ public:
   void initWARegs();
   void setWAReg(unsigned VReg, unsigned WAReg) {
     assert(WAReg != UnusedReg);
+    assert(TargetRegisterInfo::virtReg2Index(VReg) < WARegs.size());
     WARegs[TargetRegisterInfo::virtReg2Index(VReg)] = WAReg;
   }
   unsigned getWAReg(unsigned VReg) const {
+    assert(TargetRegisterInfo::virtReg2Index(VReg) < WARegs.size());
     return WARegs[TargetRegisterInfo::virtReg2Index(VReg)];
   }
+  // If new virtual registers are created after initWARegs has been called,
+  // this function can be used to add WebAssembly register mappings for them.
+  void addWAReg(unsigned VReg, unsigned WAReg) {
+    assert(VReg = WARegs.size());
+    WARegs.push_back(WAReg);
+  }
 };
 
 } // end namespace llvm
diff --git a/llvm/lib/Target/WebAssembly/WebAssemblyPeephole.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyPeephole.cpp
index 139956225b9..e149d9cce71 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyPeephole.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyPeephole.cpp
@@ -69,6 +69,7 @@ bool WebAssemblyPeephole::runOnMachineFunction(MachineFunction &MF) {
           MO.setReg(NewReg);
           MO.setIsDead();
           MFI.stackifyVReg(NewReg);
+          MFI.addWAReg(NewReg, WebAssemblyFunctionInfo::UnusedReg);
         }
       }
       }