Apply the no-r0 register class to the PPC SELECT_CC_I[4|8] pseudos

Either operand of these pseudo instructions can be transformed into the first
operand of an isel instruction (and this operand cannot be r0).

This is not yet testable because we don't yet allocate r0 (and even when we do,
any test would be very fragile).

llvm-svn: 178119

diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.td b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
index 3eda1c9..44ac0b2 100644 (file)
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.td
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
@@ -443,10 +443,15 @@ def DYNALLOC : Pseudo<(outs GPRC:$result), (ins GPRC:$negsize, memri:$fpsi), "#D
 // instruction selection into a branch sequence.
 let usesCustomInserter = 1,    // Expanded after instruction selection.
     PPC970_Single = 1 in {
-  def SELECT_CC_I4 : Pseudo<(outs GPRC:$dst), (ins CRRC:$cond, GPRC:$T, GPRC:$F,
+  // Note that SELECT_CC_I4 and SELECT_CC_I8 use the no-r0 register classes
+  // because either operand might become the first operand in an isel, and
+  // that operand cannot be r0.
+  def SELECT_CC_I4 : Pseudo<(outs GPRC:$dst), (ins CRRC:$cond,
+                              GPRC_NOR0:$T, GPRC_NOR0:$F,
                               i32imm:$BROPC), "#SELECT_CC_I4",
                               []>;
-  def SELECT_CC_I8 : Pseudo<(outs G8RC:$dst), (ins CRRC:$cond, G8RC:$T, G8RC:$F,
+  def SELECT_CC_I8 : Pseudo<(outs G8RC:$dst), (ins CRRC:$cond,
+                              G8RC_NOX0:$T, G8RC_NOX0:$F,
                               i32imm:$BROPC), "#SELECT_CC_I8",
                               []>;
   def SELECT_CC_F4  : Pseudo<(outs F4RC:$dst), (ins CRRC:$cond, F4RC:$T, F4RC:$F,