R600/SI: Fix suspicious indexing

The loop is over the operands of an instruction, and checks the
register with the sub reg index of the dest register. This probably
meant to be checking the sub reg index of the same operand.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223205 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/R600/SIFixSGPRCopies.cpp b/lib/Target/R600/SIFixSGPRCopies.cpp
index c7a16f4c3878eea9a94997afd80e622ad931a257..d90f09d3cd696f463b0fe3082f6f8334fdb8f7cb 100644 (file)
--- a/lib/Target/R600/SIFixSGPRCopies.cpp
+++ b/lib/Target/R600/SIFixSGPRCopies.cpp
@@ -219,11 +219,13 @@ bool SIFixSGPRCopies::runOnMachineFunction(MachineFunction &MF) {
       case AMDGPU::PHI: {
         DEBUG(dbgs() << "Fixing PHI: " << MI);
 
-        for (unsigned i = 1; i < MI.getNumOperands(); i+=2) {
-          unsigned Reg = MI.getOperand(i).getReg();
-          const TargetRegisterClass *RC = inferRegClassFromDef(TRI, MRI, Reg,
-                                                  MI.getOperand(0).getSubReg());
-          MRI.constrainRegClass(Reg, RC);
+        for (unsigned i = 1; i < MI.getNumOperands(); i += 2) {
+          const MachineOperand &Op = MI.getOperand(i);
+          unsigned Reg = Op.getReg();
+          const TargetRegisterClass *RC
+            = inferRegClassFromDef(TRI, MRI, Reg, Op.getSubReg());
+
+          MRI.constrainRegClass(Op.getReg(), RC);
         }
         unsigned Reg = MI.getOperand(0).getReg();
         const TargetRegisterClass *RC = inferRegClassFromUses(TRI, MRI, Reg,