[LLVMdev] Implementing llvm.atomic.cmp.swap.i32 on PowerPC

Gary Benson gbenson at redhat.com
Fri Jun 27 08:27:51 PDT 2008

Hi all,

I'm trying to figure out how to add the instructions required for
llvm.atomic.cmp.swap.i32 on PowerPC.  I figured out LWARX (patch
attached) but the other two (CMP_UNRESw and STWCX) require multiple

  let Defs = [CR0] in {
  def STWCX : Pseudo<(outs), (ins GPRC:$rS, memrr:$dst, i32imm:$label),
                    "stwcx. $rS, $dst\n\tbne- La${label}_entry\nLa${label}_exit:",
                     [(PPCstcx GPRC:$rS, xoaddr:$dst, imm:$label)]>;
  def CMP_UNRESw : Pseudo<(outs), (ins GPRC:$rA, GPRC:$rB, i32imm:$label),
                           "cmpw $rA, $rB\n\tbne- La${label}_exit",
                           [(PPCcmp_unres GPRC:$rA, GPRC:$rB, imm:$label)]>;

...and I can't figure out the syntax for that.  Any suggestions?


-------------- next part --------------
Index: lib/Target/PowerPC/PPCInstrInfo.td
--- lib/Target/PowerPC/PPCInstrInfo.td	(revision 52823)
+++ lib/Target/PowerPC/PPCInstrInfo.td	(working copy)
@@ -531,8 +531,8 @@
 // Atomic operations.
-def LWARX : Pseudo<(outs GPRC:$rD), (ins memrr:$ptr, i32imm:$label),
-                   "\nLa${label}_entry:\n\tlwarx $rD, $ptr",
+def LWARX : XForm_1<31,  20, (outs GPRC:$rD), (ins memrr:$ptr, i32imm:$label),
+                   "\nLa${label}_entry:\n\tlwarx $rD, $ptr", LdStLWARX,
                    [(set GPRC:$rD, (PPClarx xoaddr:$ptr, imm:$label))]>;
 let Defs = [CR0] in {

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