diff mbox series

i386: Fix atomic FP peepholes [PR100182]

Message ID CAFULd4bPwzXn4B29QSxZnjtXu=9WLrjcTjqXN-d2GneJvP9=Rw@mail.gmail.com
State New
Headers show
Series i386: Fix atomic FP peepholes [PR100182] | expand

Commit Message

Uros Bizjak April 23, 2021, 3:28 p.m. UTC 
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.

2021-04-23  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.

Bootstrapped and regression tested on x86_64-linux-gnu {,-m32}.

Pushed to mainline, will be pushed to other release branches once gcc-11 opens.

Uros.
diff mbox series

Patch

diff --git a/gcc/config/i386/sync.md b/gcc/config/i386/sync.md
index c7c508c8de8..7913b918796 100644
--- 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
index 00000000000..2f92a04db73
--- /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 be0b7602a8c..02c0dcb80b6 100644
--- 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 65c139849d5..bf37a8cbb71 100644
--- 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 *-*-* } } } */