Improve atomic store implementation on hppa-linux.

2021-12-27  John David Anglin  <danglin@gcc.gnu.org>

gcc/ChangeLog:

	* config/pa/pa-protos.h: Delete
	pa_maybe_emit_compare_and_swap_exchange_loop() declaration.
	* config/pa/pa.c (pa_expand_compare_and_swap_loop): Delete.
	(pa_maybe_emit_compare_and_swap_exchange_loop): Delete.
	* config/pa/pa.md (atomic_storeq): Use __sync_lock_test_and_set
	instead of pa_maybe_emit_compare_and_swap_exchange_loop.
	(atomic_storehi, atomic_storesi, atomic_storedi): Likewise.

3 files changed, 24 insertions, 93 deletions

diff --git a/gcc/config/pa/pa-protos.h b/gcc/config/pa/pa-protos.h
index 5bf6fef..69377db 100644
--- a/gcc/config/pa/pa-protos.h
+++ b/gcc/config/pa/pa-protos.h
@@ -73,7 +73,6 @@ extern rtx pa_return_addr_rtx (int, rtx);
 
 extern int pa_insn_refs_are_delayed (rtx_insn *);
 extern rtx pa_get_deferred_plabel (rtx);
-extern rtx pa_maybe_emit_compare_and_swap_exchange_loop (rtx, rtx, rtx);
 #endif /* RTX_CODE */
 
 extern int pa_and_mask_p (unsigned HOST_WIDE_INT);
diff --git a/gcc/config/pa/pa.c b/gcc/config/pa/pa.c
index 2b10ef3..895978a 100644
--- a/gcc/config/pa/pa.c
+++ b/gcc/config/pa/pa.c
@@ -11023,82 +11023,6 @@ pa_output_addr_diff_vec (rtx lab, rtx body)
     fputs ("\t.end_brtab\n", asm_out_file);
 }
 
-/* This is a helper function for the other atomic operations.  This function
-   emits a loop that contains SEQ that iterates until a compare-and-swap
-   operation at the end succeeds.  MEM is the memory to be modified.  SEQ is
-   a set of instructions that takes a value from OLD_REG as an input and
-   produces a value in NEW_REG as an output.  Before SEQ, OLD_REG will be
-   set to the current contents of MEM.  After SEQ, a compare-and-swap will
-   attempt to update MEM with NEW_REG.  The function returns true when the
-   loop was generated successfully.  */
-
-static bool
-pa_expand_compare_and_swap_loop (rtx mem, rtx old_reg, rtx new_reg, rtx seq)
-{
-  machine_mode mode = GET_MODE (mem);
-  rtx_code_label *label;
-  rtx cmp_reg, success, oldval;
-
-  /* The loop we want to generate looks like
-
-        cmp_reg = mem;
-      label:
-        old_reg = cmp_reg;
-        seq;
-        (success, cmp_reg) = compare-and-swap(mem, old_reg, new_reg)
-        if (success)
-          goto label;
-
-     Note that we only do the plain load from memory once.  Subsequent
-     iterations use the value loaded by the compare-and-swap pattern.  */
-
-  label = gen_label_rtx ();
-  cmp_reg = gen_reg_rtx (mode);
-
-  emit_move_insn (cmp_reg, mem);
-  emit_label (label);
-  emit_move_insn (old_reg, cmp_reg);
-  if (seq)
-    emit_insn (seq);
-
-  success = NULL_RTX;
-  oldval = cmp_reg;
-  if (!expand_atomic_compare_and_swap (&success, &oldval, mem, old_reg,
-                                       new_reg, false, MEMMODEL_SYNC_SEQ_CST,
-                                       MEMMODEL_RELAXED))
-    return false;
-
-  if (oldval != cmp_reg)
-    emit_move_insn (cmp_reg, oldval);
-
-  /* Mark this jump predicted not taken.  */
-  emit_cmp_and_jump_insns (success, const0_rtx, EQ, const0_rtx,
-                           GET_MODE (success), 1, label,
-			   profile_probability::guessed_never ());
-  return true;
-}
-
-/* This function tries to implement an atomic exchange operation using a 
-   compare_and_swap loop. VAL is written to *MEM.  The previous contents of
-   *MEM are returned, using TARGET if possible.  No memory model is required
-   since a compare_and_swap loop is seq-cst.  */
-
-rtx
-pa_maybe_emit_compare_and_swap_exchange_loop (rtx target, rtx mem, rtx val)
-{
-  machine_mode mode = GET_MODE (mem);
-
-  if (can_compare_and_swap_p (mode, true))
-    {
-      if (!target || !register_operand (target, mode))
-        target = gen_reg_rtx (mode);
-      if (pa_expand_compare_and_swap_loop (mem, target, val, NULL_RTX))
-        return target;
-    }
-
-  return NULL_RTX;
-}
-
 /* Implement TARGET_CALLEE_COPIES.  The callee is responsible for copying
    arguments passed by hidden reference in the 32-bit HP runtime.  Users
    can override this behavior for better compatibility with openmp at the
diff --git a/gcc/config/pa/pa.md b/gcc/config/pa/pa.md
index f124c30..af5449a 100644
--- a/gcc/config/pa/pa.md
+++ b/gcc/config/pa/pa.md
@@ -10366,10 +10366,12 @@ add,l %2,%3,%3\;bv,n %%r0(%3)"
 {
   if (TARGET_SYNC_LIBCALL)
     {
-      rtx mem = operands[0];
-      rtx val = operands[1];
-      if (pa_maybe_emit_compare_and_swap_exchange_loop (NULL_RTX, mem, val))
-	DONE;
+      rtx libfunc = init_one_libfunc ("__sync_lock_test_and_set_1");
+
+      emit_library_call (libfunc, LCT_NORMAL, VOIDmode,
+			 XEXP (operands[0], 0), Pmode,
+			 operands[1], QImode);
+      DONE;
     }
   FAIL;
 })
@@ -10384,10 +10386,12 @@ add,l %2,%3,%3\;bv,n %%r0(%3)"
 {
   if (TARGET_SYNC_LIBCALL)
     {
-      rtx mem = operands[0];
-      rtx val = operands[1];
-      if (pa_maybe_emit_compare_and_swap_exchange_loop (NULL_RTX, mem, val))
-	DONE;
+      rtx libfunc = init_one_libfunc ("__sync_lock_test_and_set_2");
+
+      emit_library_call (libfunc, LCT_NORMAL, VOIDmode,
+			 XEXP (operands[0], 0), Pmode,
+			 operands[1], HImode);
+      DONE;
     }
   FAIL;
 })
@@ -10402,10 +10406,12 @@ add,l %2,%3,%3\;bv,n %%r0(%3)"
 {
   if (TARGET_SYNC_LIBCALL)
     {
-      rtx mem = operands[0];
-      rtx val = operands[1];
-      if (pa_maybe_emit_compare_and_swap_exchange_loop (NULL_RTX, mem, val))
-	DONE;
+      rtx libfunc = init_one_libfunc ("__sync_lock_test_and_set_4");
+
+      emit_library_call (libfunc, LCT_NORMAL, VOIDmode,
+			 XEXP (operands[0], 0), Pmode,
+			 operands[1], SImode);
+      DONE;
     }
   FAIL;
 })
@@ -10453,10 +10459,12 @@ add,l %2,%3,%3\;bv,n %%r0(%3)"
 
   if (TARGET_SYNC_LIBCALL)
     {
-      rtx mem = operands[0];
-      rtx val = operands[1];
-      if (pa_maybe_emit_compare_and_swap_exchange_loop (NULL_RTX, mem, val))
-	DONE;
+      rtx libfunc = init_one_libfunc ("__sync_lock_test_and_set_8");
+
+      emit_library_call (libfunc, LCT_NORMAL, VOIDmode,
+			 XEXP (operands[0], 0), Pmode,
+			 operands[1], DImode);
+      DONE;
     }
 
   if (TARGET_64BIT || TARGET_SOFT_FLOAT)