Re-committing r130454, which does not in fact break anything.

Fix a rather obscure crash caused by ARM fast-isel generating code which redefines a register.
rdar://problem/9338332 .

llvm-svn: 130539

lib/Target/ARM/ARMFastISel.cpp

@@ -822,26 +822,9 @@ void ARMFastISel::ARMSimplifyAddress(Address &Addr, EVT VT) {
   // Since the offset is too large for the load/store instruction
   // get the reg+offset into a register.
   if (needsLowering) {
-    ARMCC::CondCodes Pred = ARMCC::AL;
-    unsigned PredReg = 0;
-
-    TargetRegisterClass *RC = isThumb ? ARM::tGPRRegisterClass :
-      ARM::GPRRegisterClass;
-    unsigned BaseReg = createResultReg(RC);
-
-    if (!isThumb)
-      emitARMRegPlusImmediate(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
-                              BaseReg, Addr.Base.Reg, Addr.Offset,
-                              Pred, PredReg,
-                              static_cast<const ARMBaseInstrInfo&>(TII));
-    else {
-      assert(AFI->isThumb2Function());
-      emitT2RegPlusImmediate(*FuncInfo.MBB, FuncInfo.InsertPt, DL,
-                             BaseReg, Addr.Base.Reg, Addr.Offset, Pred, PredReg,
-                             static_cast<const ARMBaseInstrInfo&>(TII));
-    }
+    Addr.Base.Reg = FastEmit_ri_(MVT::i32, ISD::ADD, Addr.Base.Reg,
+                                 /*Op0IsKill*/false, Addr.Offset, MVT::i32);
     Addr.Offset = 0;
-    Addr.Base.Reg = BaseReg;
   }
 }
 

test/CodeGen/ARM/fast-isel-redefinition.ll

@@ -0,0 +1,11 @@
+; RUN: llc -O0 -regalloc=linearscan | grep "ldr r0"
+; This isn't exactly a useful set of command-line options, but check that it
+; doesn't crash.  (It was crashing because a register was getting redefined.)
+
+target triple = "thumbv7-apple-macosx10.6.7"
+
+define i32 @f(i32* %x) nounwind ssp {
+  %y = getelementptr inbounds i32* %x, i32 5000
+  %tmp103 = load i32* %y, align 4
+  ret i32 %tmp103
+}