Move and adjust PROBE_STACK reg definitions for aarch64

The change moves the definitions of PROBE_STACK_FIRST_REG
and PROBE_STACK_SECOND_REG to a more appropriate place for such
items (here, in aarch64.md as suggested by Richard), and adjusts
their value from r9/r10 to r10/r11 to free r9 for a possibly
more general purpose (e.g. as a static chain at least on targets
which have a private use of r18, such as Windows or Vxworks).

2020-11-07  Olivier Hainque  <hainque@adacore.com>

gcc/
	* config/aarch64/aarch64.md: Define PROBE_STACK_FIRST_REGNUM
	and PROBE_STACK_SECOND_REGNUM constants, designating r10/r11.
	Replacements for the PROBE_STACK_FIRST/SECOND_REG constants in
	aarch64.c.
	* config/aarch64/aarch64.c (PROBE_STACK_FIRST_REG): Remove.
	(PROBE_STACK_SECOND_REG): Remove.
	(aarch64_emit_probe_stack_range): Adjust to the _REG -> _REGNUM
	suffix update for PROBE_STACK register numbers.

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 27f587be7e7483093f1fd381d8fa14a6c6581ccf..0ae6c8b53f6e7ae629bafc2ec033a440012cbe42 100644 (file)
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -6272,10 +6272,6 @@ aarch64_libgcc_cmp_return_mode (void)
 #error Cannot use simple address calculation for stack probing
 #endif
 
-/* The pair of scratch registers used for stack probing.  */
-#define PROBE_STACK_FIRST_REG  R9_REGNUM
-#define PROBE_STACK_SECOND_REG R10_REGNUM
-
 /* Emit code to probe a range of stack addresses from FIRST to FIRST+POLY_SIZE,
    inclusive.  These are offsets from the current stack pointer.  */
 
@@ -6289,7 +6285,7 @@ aarch64_emit_probe_stack_range (HOST_WIDE_INT first, poly_int64 poly_size)
       return;
     }
 
-  rtx reg1 = gen_rtx_REG (Pmode, PROBE_STACK_FIRST_REG);
+  rtx reg1 = gen_rtx_REG (Pmode, PROBE_STACK_FIRST_REGNUM);
 
   /* See the same assertion on PROBE_INTERVAL above.  */
   gcc_assert ((first % ARITH_FACTOR) == 0);
@@ -6347,7 +6343,7 @@ aarch64_emit_probe_stack_range (HOST_WIDE_INT first, poly_int64 poly_size)
      equality test for the loop condition.  */
   else
     {
-      rtx reg2 = gen_rtx_REG (Pmode, PROBE_STACK_SECOND_REG);
+      rtx reg2 = gen_rtx_REG (Pmode, PROBE_STACK_SECOND_REGNUM);
 
       /* Step 1: round SIZE to the previous multiple of the interval.  */
 

diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md
index 78fe7c43a00432861e59f19330dacec234b58875..11e0f4612be4117ca59ae56edaea7d08322ddfa5 100644 (file)
--- a/gcc/config/aarch64/aarch64.md
+++ b/gcc/config/aarch64/aarch64.md
@@ -111,6 +111,13 @@
     ;; "FFR token": a fake register used for representing the scheduling
     ;; restrictions on FFR-related operations.
     (FFRT_REGNUM       85)
+    ;; The pair of scratch registers used for stack probing with -fstack-check.
+    ;; Leave R9 alone as a possible choice for the static chain.
+    ;; Note that the use of these registers is mutually exclusive with the use
+    ;; of STACK_CLASH_SVE_CFA_REGNUM, which is for -fstack-clash-protection
+    ;; rather than -fstack-check.
+    (PROBE_STACK_FIRST_REGNUM  10)
+    (PROBE_STACK_SECOND_REGNUM 11)
     ;; Scratch register used by stack clash protection to calculate
     ;; SVE CFA offsets during probing.
     (STACK_CLASH_SVE_CFA_REGNUM 11)