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[PTX] atomics compare exchange

Message ID 55F03DBB.4090108@acm.org
State New
Headers show

Commit Message

Nathan Sidwell Sept. 9, 2015, 2:10 p.m. UTC 
I noticed the atomic compare exchange was using 'and 1' to generate a bool.  We 
now have select, which makes it more obvious.

Sadly  the middle end's expansion of of the builtin fails to make use of the 
condition we just generated directly, instead generating a new one from the bool.

nathan
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Patch

2015-09-09  Nathan Sidwell  <nathan@acm.org>

	* config/nvptx/nvptx.md (atomic_compare_and_swap<mode>): Use
	sel_truesi, not andsi.

Index: gcc/config/nvptx/nvptx.md
===================================================================
--- gcc/config/nvptx/nvptx.md	(revision 227568)
+++ gcc/config/nvptx/nvptx.md	(working copy)
@@ -1351,14 +1351,12 @@ 
    (match_operand:SI 7 "const_int_operand")]		;; failure model
   ""
 {
-  emit_insn (gen_atomic_compare_and_swap<mode>_1 (operands[1], operands[2], operands[3],
-					          operands[4], operands[6]));
+  emit_insn (gen_atomic_compare_and_swap<mode>_1
+    (operands[1], operands[2], operands[3], operands[4], operands[6]));
 
-  rtx tmp = gen_reg_rtx (GET_MODE (operands[0]));
-  emit_insn (gen_cstore<mode>4 (tmp,
-				gen_rtx_EQ (SImode, operands[1], operands[3]),
-				operands[1], operands[3]));
-  emit_insn (gen_andsi3 (operands[0], tmp, GEN_INT (1)));
+  rtx cond = gen_reg_rtx (BImode);
+  emit_move_insn (cond, gen_rtx_EQ (BImode, operands[1], operands[3]));
+  emit_insn (gen_sel_truesi (operands[0], cond, GEN_INT (1), GEN_INT (0)));
   DONE;
 })