R600/SI: Disable copying of SCC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219519 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/R600/SIRegisterInfo.td b/lib/Target/R600/SIRegisterInfo.td
index 7e00a73..799810d 100644 (file)
--- a/lib/Target/R600/SIRegisterInfo.td
+++ b/lib/Target/R600/SIRegisterInfo.td
@@ -170,7 +170,11 @@ def VGPR_512 : RegisterTuples<[sub0, sub1, sub2, sub3, sub4, sub5, sub6, sub7,
 //===----------------------------------------------------------------------===//
 
 // Special register classes for predicates and the M0 register
-def SCCReg : RegisterClass<"AMDGPU", [i32, i1], 32, (add SCC)>;
+def SCCReg : RegisterClass<"AMDGPU", [i32, i1], 32, (add SCC)> {
+  let CopyCost = -1; // Theoretically it is possible to read from SCC,
+                     // but it should never be necessary.
+}
+
 def VCCReg : RegisterClass<"AMDGPU", [i64, i1], 64, (add VCC)>;
 def EXECReg : RegisterClass<"AMDGPU", [i64, i1], 64, (add EXEC)>;
 def M0Reg : RegisterClass<"AMDGPU", [i32], 32, (add M0)>;