aarch64: Tidy aarch64_split_compare_and_swap

2020-04-01  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

	Backport from mainline
	2019-09-19  Richard Henderson  <richard.henderson@linaro.org>

	* config/aarch64/aarch64 (aarch64_split_compare_and_swap): Disable
	strong_zero_p for aarch64_track_speculation; unify some code paths;
	use aarch64_gen_compare_reg instead of open-coding.

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index de711d5192eea1246a578be43140f4c5b9a4702f..6f1e40c1f1c8274cd4767896b0fdb883ed07c93a 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2020-04-01  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
+
+       Backport from mainline
+       2019-09-19  Richard Henderson  <richard.henderson@linaro.org>
+
+       * config/aarch64/aarch64 (aarch64_split_compare_and_swap): Disable
+       strong_zero_p for aarch64_track_speculation; unify some code paths;
+       use aarch64_gen_compare_reg instead of open-coding.
+
 2020-04-01  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>
 
        Backport from mainline

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index ae9f567cac7a7a9c00fd8467aec9cd8b4f86de9c..d5515f859e5bd05ecc299f1aa68d838006931f0e 100644 (file)
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -15573,13 +15573,11 @@ aarch64_split_compare_and_swap (rtx operands[])
   /* Split after prolog/epilog to avoid interactions with shrinkwrapping.  */
   gcc_assert (epilogue_completed);
 
-  rtx rval, mem, oldval, newval, scratch;
+  rtx rval, mem, oldval, newval, scratch, x, model_rtx;
   machine_mode mode;
   bool is_weak;
   rtx_code_label *label1, *label2;
-  rtx x, cond;
   enum memmodel model;
-  rtx model_rtx;
 
   rval = operands[0];
   mem = operands[1];
@@ -15600,7 +15598,8 @@ aarch64_split_compare_and_swap (rtx operands[])
        CBNZ    scratch, .label1
     .label2:
        CMP     rval, 0.  */
-  bool strong_zero_p = !is_weak && oldval == const0_rtx && mode != TImode;
+  bool strong_zero_p = (!is_weak && !aarch64_track_speculation &&
+                       oldval == const0_rtx && mode != TImode);
 
   label1 = NULL;
   if (!is_weak)
@@ -15613,35 +15612,20 @@ aarch64_split_compare_and_swap (rtx operands[])
   /* The initial load can be relaxed for a __sync operation since a final
      barrier will be emitted to stop code hoisting.  */
   if (is_mm_sync (model))
-    aarch64_emit_load_exclusive (mode, rval, mem,
-                                GEN_INT (MEMMODEL_RELAXED));
+    aarch64_emit_load_exclusive (mode, rval, mem, GEN_INT (MEMMODEL_RELAXED));
   else
     aarch64_emit_load_exclusive (mode, rval, mem, model_rtx);
 
   if (strong_zero_p)
-    {
-      if (aarch64_track_speculation)
-       {
-         /* Emit an explicit compare instruction, so that we can correctly
-            track the condition codes.  */
-         rtx cc_reg = aarch64_gen_compare_reg (NE, rval, const0_rtx);
-         x = gen_rtx_NE (GET_MODE (cc_reg), cc_reg, const0_rtx);
-       }
-      else
-       x = gen_rtx_NE (VOIDmode, rval, const0_rtx);
-
-      x = gen_rtx_IF_THEN_ELSE (VOIDmode, x,
-                               gen_rtx_LABEL_REF (Pmode, label2), pc_rtx);
-      aarch64_emit_unlikely_jump (gen_rtx_SET (pc_rtx, x));
-    }
+    x = gen_rtx_NE (VOIDmode, rval, const0_rtx);
   else
     {
-      cond = aarch64_gen_compare_reg_maybe_ze (NE, rval, oldval, mode);
-      x = gen_rtx_NE (VOIDmode, cond, const0_rtx);
-      x = gen_rtx_IF_THEN_ELSE (VOIDmode, x,
-                               gen_rtx_LABEL_REF (Pmode, label2), pc_rtx);
-      aarch64_emit_unlikely_jump (gen_rtx_SET (pc_rtx, x));
+      rtx cc_reg = aarch64_gen_compare_reg_maybe_ze (NE, rval, oldval, mode);
+      x = gen_rtx_NE (VOIDmode, cc_reg, const0_rtx);
     }
+  x = gen_rtx_IF_THEN_ELSE (VOIDmode, x,
+                           gen_rtx_LABEL_REF (Pmode, label2), pc_rtx);
+  aarch64_emit_unlikely_jump (gen_rtx_SET (pc_rtx, x));
 
   aarch64_emit_store_exclusive (mode, scratch, mem, newval, model_rtx);
 
@@ -15662,22 +15646,16 @@ aarch64_split_compare_and_swap (rtx operands[])
       aarch64_emit_unlikely_jump (gen_rtx_SET (pc_rtx, x));
     }
   else
-    {
-      cond = gen_rtx_REG (CCmode, CC_REGNUM);
-      x = gen_rtx_COMPARE (CCmode, scratch, const0_rtx);
-      emit_insn (gen_rtx_SET (cond, x));
-    }
+    aarch64_gen_compare_reg (NE, scratch, const0_rtx);
 
   emit_label (label2);
+
   /* If we used a CBNZ in the exchange loop emit an explicit compare with RVAL
      to set the condition flags.  If this is not used it will be removed by
      later passes.  */
   if (strong_zero_p)
-    {
-      cond = gen_rtx_REG (CCmode, CC_REGNUM);
-      x = gen_rtx_COMPARE (CCmode, rval, const0_rtx);
-      emit_insn (gen_rtx_SET (cond, x));
-    }
+    aarch64_gen_compare_reg (NE, rval, const0_rtx);
+
   /* Emit any final barrier needed for a __sync operation.  */
   if (is_mm_sync (model))
     aarch64_emit_post_barrier (model);