i386: Fix atomic FP peepholes [PR100182]

64bit loads to/stores from x87 and SSE registers are atomic also on 32-bit
targets, so there is no need for additional atomic moves to a temporary
register.

Introduced load peephole2 patterns assume that there won't be any additional
loads from the load location outside the peepholed sequence and wrongly
removed the source location initialization.

OTOH, introduced store peephole2 patterns assume there won't be any additional
loads from the stored location outside the peepholed sequence and wrongly
removed the destination location initialization.  Note that we can't use plain
x87 FST instruction to initialize destination location because FST converts
the value to the double-precision format, changing bits during move.

The patch restores removed initializations in load and store patterns.
Additionally, plain x87 FST in store peephole2 patterns is prevented by
limiting the store operand source to SSE registers.

2021-04-27  Uroš Bizjak  <ubizjak@gmail.com>

gcc/
	PR target/100182
	* config/i386/sync.md (FILD_ATOMIC/FIST_ATOMIC FP load peephole2):
	Copy operand 3 to operand 4.  Use sse_reg_operand
	as operand 3 predicate.
	(FILD_ATOMIC/FIST_ATOMIC FP load peephole2 with mem blockage): Ditto.
	(LDX_ATOMIC/STX_ATOMIC FP load peephole2): Ditto.
	(LDX_ATOMIC/LDX_ATOMIC FP load peephole2 with mem blockage): Ditto.
	(FILD_ATOMIC/FIST_ATOMIC FP store peephole2):
	Copy operand 1 to operand 0.
	(FILD_ATOMIC/FIST_ATOMIC FP store peephole2 with mem blockage): Ditto.
	(LDX_ATOMIC/STX_ATOMIC FP store peephole2): Ditto.
	(LDX_ATOMIC/LDX_ATOMIC FP store peephole2 with mem blockage): Ditto.

gcc/testsuite/
	PR target/100182
	* gcc.target/i386/pr100182.c: New test.
	* gcc.target/i386/pr71245-1.c (dg-final): Xfail scan-assembler-not.
	* gcc.target/i386/pr71245-2.c (dg-final): Ditto.

diff --git a/gcc/config/i386/sync.md b/gcc/config/i386/sync.md
index c7c508c8de860035f9938ec9fa58abb0f554bf4a..7913b918796ae8656e89a9290cc6fba5eb132cac 100644 (file)
--- a/gcc/config/i386/sync.md
+++ b/gcc/config/i386/sync.md
@@ -226,12 +226,13 @@
    (set (match_operand:DI 2 "memory_operand")
        (unspec:DI [(match_dup 0)]
                   UNSPEC_FIST_ATOMIC))
-   (set (match_operand:DF 3 "any_fp_register_operand")
+   (set (match_operand:DF 3 "sse_reg_operand")
        (match_operand:DF 4 "memory_operand"))]
   "!TARGET_64BIT
    && peep2_reg_dead_p (2, operands[0])
    && rtx_equal_p (XEXP (operands[4], 0), XEXP (operands[2], 0))"
-  [(set (match_dup 3) (match_dup 5))]
+  [(set (match_dup 3) (match_dup 5))
+   (set (match_dup 4) (match_dup 3))]
   "operands[5] = gen_lowpart (DFmode, operands[1]);")
 
 (define_peephole2
@@ -243,7 +244,7 @@
                   UNSPEC_FIST_ATOMIC))
    (set (mem:BLK (scratch:SI))
        (unspec:BLK [(mem:BLK (scratch:SI))] UNSPEC_MEMORY_BLOCKAGE))
-   (set (match_operand:DF 3 "any_fp_register_operand")
+   (set (match_operand:DF 3 "sse_reg_operand")
        (match_operand:DF 4 "memory_operand"))]
   "!TARGET_64BIT
    && peep2_reg_dead_p (2, operands[0])
@@ -251,6 +252,7 @@
   [(const_int 0)]
 {
   emit_move_insn (operands[3], gen_lowpart (DFmode, operands[1]));
+  emit_move_insn (operands[4], operands[3]);
   emit_insn (gen_memory_blockage ());
   DONE;
 })
@@ -262,12 +264,13 @@
    (set (match_operand:DI 2 "memory_operand")
        (unspec:DI [(match_dup 0)]
                   UNSPEC_STX_ATOMIC))
-   (set (match_operand:DF 3 "any_fp_register_operand")
+   (set (match_operand:DF 3 "sse_reg_operand")
        (match_operand:DF 4 "memory_operand"))]
   "!TARGET_64BIT
    && peep2_reg_dead_p (2, operands[0])
    && rtx_equal_p (XEXP (operands[4], 0), XEXP (operands[2], 0))"
-  [(set (match_dup 3) (match_dup 5))]
+  [(set (match_dup 3) (match_dup 5))
+   (set (match_dup 4) (match_dup 3))]
   "operands[5] = gen_lowpart (DFmode, operands[1]);")
 
 (define_peephole2
@@ -279,7 +282,7 @@
                   UNSPEC_STX_ATOMIC))
    (set (mem:BLK (scratch:SI))
        (unspec:BLK [(mem:BLK (scratch:SI))] UNSPEC_MEMORY_BLOCKAGE))
-   (set (match_operand:DF 3 "any_fp_register_operand")
+   (set (match_operand:DF 3 "sse_reg_operand")
        (match_operand:DF 4 "memory_operand"))]
   "!TARGET_64BIT
    && peep2_reg_dead_p (2, operands[0])
@@ -287,6 +290,7 @@
   [(const_int 0)]
 {
   emit_move_insn (operands[3], gen_lowpart (DFmode, operands[1]));
+  emit_move_insn (operands[4], operands[3]);
   emit_insn (gen_memory_blockage ());
   DONE;
 })
@@ -392,7 +396,8 @@
   "!TARGET_64BIT
    && peep2_reg_dead_p (3, operands[2])
    && rtx_equal_p (XEXP (operands[0], 0), XEXP (operands[3], 0))"
-  [(set (match_dup 5) (match_dup 1))]
+  [(set (match_dup 0) (match_dup 1))
+   (set (match_dup 5) (match_dup 1))]
   "operands[5] = gen_lowpart (DFmode, operands[4]);")
 
 (define_peephole2
@@ -411,6 +416,7 @@
    && rtx_equal_p (XEXP (operands[0], 0), XEXP (operands[3], 0))"
   [(const_int 0)]
 {
+  emit_move_insn (operands[0], operands[1]);
   emit_insn (gen_memory_blockage ());
   emit_move_insn (gen_lowpart (DFmode, operands[4]), operands[1]);
   DONE;
@@ -428,7 +434,8 @@
   "!TARGET_64BIT
    && peep2_reg_dead_p (3, operands[2])
    && rtx_equal_p (XEXP (operands[0], 0), XEXP (operands[3], 0))"
-  [(set (match_dup 5) (match_dup 1))]
+  [(set (match_dup 0) (match_dup 1))
+   (set (match_dup 5) (match_dup 1))]
   "operands[5] = gen_lowpart (DFmode, operands[4]);")
 
 (define_peephole2
@@ -447,6 +454,7 @@
    && rtx_equal_p (XEXP (operands[0], 0), XEXP (operands[3], 0))"
   [(const_int 0)]
 {
+  emit_move_insn (operands[0], operands[1]);
   emit_insn (gen_memory_blockage ());
   emit_move_insn (gen_lowpart (DFmode, operands[4]), operands[1]);
   DONE;

diff --git a/gcc/testsuite/gcc.target/i386/pr100182.c b/gcc/testsuite/gcc.target/i386/pr100182.c
new file mode 100644 (file)
index 0000000..2f92a04
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr100182.c
@@ -0,0 +1,30 @@
+/* { dg-do run { target ia32 } } */
+/* { dg-options "-O2 -march=i686" } */
+
+struct S { double _M_fp; };
+union U { double d; unsigned long long int l; };
+
+void
+__attribute__((noipa))
+foo (void)
+{
+  struct S a0, a1;
+  union U u;
+  double d0, d1;
+  a0._M_fp = 0.0;
+  a1._M_fp = 1.0;
+  __atomic_store_8 (&a0._M_fp, __atomic_load_8 (&a1._M_fp, __ATOMIC_SEQ_CST), __ATOMIC_SEQ_CST);
+  u.l = __atomic_load_8 (&a0._M_fp, __ATOMIC_SEQ_CST);
+  d0 = u.d;
+  u.l = __atomic_load_8 (&a1._M_fp, __ATOMIC_SEQ_CST);
+  d1 = u.d;
+  if (d0 != d1)
+    __builtin_abort ();
+}
+
+int
+main ()
+{
+  foo ();
+  return 0;
+}

diff --git a/gcc/testsuite/gcc.target/i386/pr71245-1.c b/gcc/testsuite/gcc.target/i386/pr71245-1.c
index be0b7602a8cffa9bc015986f72246580a13b0106..02c0dcb80b6591ca0610618bf6db6e764a344564 100644 (file)
--- a/gcc/testsuite/gcc.target/i386/pr71245-1.c
+++ b/gcc/testsuite/gcc.target/i386/pr71245-1.c
@@ -19,4 +19,4 @@ void foo_d (void)
   __atomic_store_n (&d.ll, tmp.ll, __ATOMIC_SEQ_CST);
 }
 
-/* { dg-final { scan-assembler-not "(fistp|fild)" } } */
+/* { dg-final { scan-assembler-not "(fistp|fild)" { xfail *-*-* } } } */

diff --git a/gcc/testsuite/gcc.target/i386/pr71245-2.c b/gcc/testsuite/gcc.target/i386/pr71245-2.c
index 65c139849d539a0448124207a683c4493a9bee14..bf37a8cbb7138265d3df78beaee817fdb9c56335 100644 (file)
--- a/gcc/testsuite/gcc.target/i386/pr71245-2.c
+++ b/gcc/testsuite/gcc.target/i386/pr71245-2.c
@@ -19,4 +19,4 @@ void foo_d (void)
   __atomic_store_n (&d.ll, tmp.ll, __ATOMIC_SEQ_CST);
 }
 
-/* { dg-final { scan-assembler-not "movlps" } } */
+/* { dg-final { scan-assembler-not "movlps" { xfail *-*-* } } } */