[mips][FastISel] Implement FastMaterializeAlloca in Mips fast-isel.

Summary: Implement the method FastMaterializeAlloca in Mips fast-isel

Based on a patch by Reed Kotler.

Test Plan:
Passes test-suite at O0/O2 for mips32 r1/r2
fastalloca.ll

Reviewers: dsanders, rkotler

Subscribers: rfuhler, llvm-commits

Differential Revision: http://reviews.llvm.org/D6742

llvm-svn: 235213

1 files changed, 20 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/MipsFastISel.cpp b/llvm/lib/Target/Mips/MipsFastISel.cpp
index 03d5ea2..4b60606 100644
--- a/llvm/lib/Target/Mips/MipsFastISel.cpp
+++ b/llvm/lib/Target/Mips/MipsFastISel.cpp
@@ -187,6 +187,7 @@ public:
     UnsupportedFPMode = Subtarget->isFP64bit();
   }
 
+  unsigned fastMaterializeAlloca(const AllocaInst *AI) override;
   unsigned fastMaterializeConstant(const Constant *C) override;
   bool fastSelectInstruction(const Instruction *I) override;
 
@@ -253,6 +254,25 @@ unsigned MipsFastISel::emitLogicalOp(unsigned ISDOpc, MVT RetVT,
   return ResultReg;
 }
 
+unsigned MipsFastISel::fastMaterializeAlloca(const AllocaInst *AI) {
+  assert(TLI.getValueType(AI->getType(), true) == MVT::i32 &&
+         "Alloca should always return a pointer.");
+
+  DenseMap<const AllocaInst *, int>::iterator SI =
+      FuncInfo.StaticAllocaMap.find(AI);
+
+  if (SI != FuncInfo.StaticAllocaMap.end()) {
+    unsigned ResultReg = createResultReg(&Mips::GPR32RegClass);
+    BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DbgLoc, TII.get(Mips::LEA_ADDiu),
+            ResultReg)
+        .addFrameIndex(SI->second)
+        .addImm(0);
+    return ResultReg;
+  }
+
+  return 0;
+}
+
 unsigned MipsFastISel::materializeInt(const Constant *C, MVT VT) {
   if (VT != MVT::i32 && VT != MVT::i16 && VT != MVT::i8 && VT != MVT::i1)
     return 0;