From: Tobias Burnus <tburnus@baylibre.com>
Date: Mon, 28 Jul 2025 10:16:02 +0000 (+0200)
Subject: gcn: Add 'nops' insn, extend comments
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9098f79ff0c559278400cbfbeb8d1101c39e8349;p=thirdparty%2Fgcc.git

gcn: Add 'nops' insn, extend comments

Use 's_nops' with a number instead of multiple of 's_nop' when
manually adding 1 to 5 wait state. This helps with
the instruction cache and helps a tiny bit with PR119367 where
a two-byte variable overflows in the debugging location view handling.

Add a comment about 'sc0' to TARGET_GLC_NAME as for atomics it is
unrelated to the scope but to whether the result is stored; i.e.
using e.g. 'sc1' instead of 'sc0' will have undesired consequences!

Update the comment above print_operand_address to document 'R' and 'V';
those are used below as "Temporary hack.", but it makes sense to see
them in the list.

gcc/ChangeLog:

	* config/gcn/gcn-opts.h (enum hsaco_attr_type): Add comment
	about 'sc0'.
	* config/gcn/gcn.cc (gcn_md_reorg): Use gen_nops instead of gen_nop.
	(print_operand_address): Document 'R' and 'V' in the
	pre-function comment as well.
	* config/gcn/gcn.md (nops): Add.
---

diff --git a/gcc/config/gcn/gcn-opts.h b/gcc/config/gcn/gcn-opts.h
index fe68678bd02..0287400fd0c 100644
--- a/gcc/config/gcn/gcn-opts.h
+++ b/gcc/config/gcn/gcn-opts.h
@@ -92,6 +92,8 @@ enum hsaco_attr_type
 /* Whether to use the 'globally coherent' (glc) or the 'scope' (sc0) flag
    for non-scalar memory operations. The string starts on purpose with a space.
    Note: for scalar memory operations (i.e. 's_...'), 'glc' is still used.
+   Note: on atomics, glc/sc0 denotes whether the pre-op operation should
+   be used.
    CDNA3 also uses 'nt' instead of 'slc' and 'sc1' instead of 'scc'; however,
    there is no non-scalar user so far.  */
 #define TARGET_GLC_NAME (TARGET_CDNA3 ? " sc0" : " glc")
diff --git a/gcc/config/gcn/gcn.cc b/gcc/config/gcn/gcn.cc
index 8959118b869..75b0936dce8 100644
--- a/gcc/config/gcn/gcn.cc
+++ b/gcc/config/gcn/gcn.cc
@@ -6436,8 +6436,8 @@ gcn_md_reorg (void)
 	}
 
       /* Insert the required number of NOPs.  */
-      for (int i = nops_rqd; i > 0; i--)
-	emit_insn_after (gen_nop (), last_insn);
+      if (nops_rqd > 0)
+	emit_insn_after (gen_nops (GEN_INT (nops_rqd-1)), last_insn);
 
       /* Age the previous instructions.  We can also ignore writes to
          registers subsequently overwritten.  */
@@ -7283,6 +7283,11 @@ print_operand_address (FILE *file, rtx mem)
    H - print second part of a multi-reg value (high-part of 2-reg value)
    J - print third part of a multi-reg value
    K - print fourth part of a multi-reg value
+   R   Print a scalar register number as an integer.  Temporary hack.
+   V - Print a vector register number as an integer.  Temporary hack.
+
+   Additionally, the standard builtin c, n, a, and l exist; see gccint's
+   "Output Templates and Operand Substitution" for details.
  */
 
 void
diff --git a/gcc/config/gcn/gcn.md b/gcc/config/gcn/gcn.md
index fad42e6a6bf..9172db08b2e 100644
--- a/gcc/config/gcn/gcn.md
+++ b/gcc/config/gcn/gcn.md
@@ -424,6 +424,15 @@
   "s_nop\t0x0"
   [(set_attr "type" "sopp")])
 
+; Variant of 'nop' that accepts a count argument.
+; s_nop accepts 0x0 to 0xf for 1 to 16 nops; however,
+; as %0 prints decimals, only 0 to 9 (= 1 to 10 nops) can be used.
+(define_insn "nops"
+  [(match_operand 0 "const_int_operand")]
+  ""
+  "s_nop\t0x%0"
+  [(set_attr "type" "sopp")])
+
 ; FIXME: What should the value of the immediate be? Zero is disallowed, so
 ; pick 1 for now.
 (define_insn "trap"