__builtin_prefetch fixes [PR117608]

The r15-4833-ge9ab41b79933 patch had among tons of config/i386
specific changes also important change to the generic code, allowing
also 2 as valid value of the second argument of __builtin_prefetch:
-  /* Argument 1 must be either zero or one.  */
-  if (INTVAL (op1) != 0 && INTVAL (op1) != 1)
+  /* Argument 1 must be 0, 1 or 2.  */
+  if (INTVAL (op1) < 0 || INTVAL (op1) > 2)

But the patch failed to document that change in __builtin_prefetch
documentation, and more importantly didn't adjust any of the other
backends to deal with it (my understanding is the expected behavior
is that 2 will be silently handled as 0 unless backends have some
more specific way).  Some of the backends would ICE on it, in some
cases gcc_assert failures/gcc_unreachable, in other cases crash later
(e.g. accessing arrays with that value as index and due to accessing
garbage after the array crashing at final.cc time), others treated 2
silently as 0, others treated 2 silently as 1.

And even in the i386 backend there were bugs which caused ICEs.
The patch added some if (write == 0) and write 2 handling into
a (badly indented, maybe that is the reason, if (write == 1) body),
rather than into the else side, so it would be always false.

The new *prefetch_rst2 define_insn only accepts parameters 2 1
(i.e. read-shared with moderate degree of locality), so in order
not to ICE the patch uses it only for __builtin_prefetch (ptr, 2, 1);
or __builtin_ia32_prefetch (ptr, 2, 1, 0); and not for other values
of the parameter.  If that isn't what we want and we want it to be used
also for all or some of __builtin_prefetch (ptr, 2, {0,2,3}); and
corresponding __builtin_ia32_prefetch, maybe the define_insn could match
other values.
And there was another problem that -mno-mmx -mno-sse -mmovrs compilation
would ICE on most of the prefetches, so I had to add the FAIL; cases.

2024-11-29  Jakub Jelinek  <jakub@redhat.com>

	PR target/117608
	* doc/extend.texi (__builtin_prefetch): Document that second
	argument may be also 2 and its meaning.
	* config/i386/i386.md (prefetch): Remove unreachable code.
	Clear write set operands[1] to const0_rtx if !TARGET_MOVRS or
	of locality is not 1.  Formatting fixes.
	* config/i386/i386-expand.cc (ix86_expand_builtin): Use IN_RANGE.
	Call gen_prefetch even for TARGET_MOVRS.
	* config/alpha/alpha.md (prefetch): Treat read_or_write 2 like 0.
	* config/mips/mips.md (prefetch): Likewise.
	* config/arc/arc.md (prefetch_1, prefetch_2, prefetch_3): Likewise.
	* config/riscv/riscv.md (prefetch): Likewise.
	* config/loongarch/loongarch.md (prefetch): Likewise.
	* config/sparc/sparc.md (prefetch): Likewise.  Use IN_RANGE.
	* config/ia64/ia64.md (prefetch): Likewise.
	* config/pa/pa.md (prefetch): Likewise.
	* config/aarch64/aarch64.md (prefetch): Likewise.
	* config/rs6000/rs6000.md (prefetch): Likewise.

	* gcc.dg/builtin-prefetch-1.c (good): Add tests with second argument
	2.
	* gcc.target/i386/pr117608-1.c: New test.
	* gcc.target/i386/pr117608-2.c: New test.

1 files changed, 7 insertions, 7 deletions

diff --git a/gcc/config/arc/arc.md b/gcc/config/arc/arc.md
index 9004b60..1fb7cf5 100644
--- a/gcc/config/arc/arc.md
+++ b/gcc/config/arc/arc.md
@@ -5439,9 +5439,9 @@ archs4x, archs4xd"
 	     (match_operand:SI 2 "const_int_operand" "n"))]
   "TARGET_HS"
   {
-   if (INTVAL (operands[1]))
+    if ((INTVAL (operands[1]) & 1) != 0)
       return "prefetchw [%0]";
-   else
+    else
       return "prefetch [%0]";
   }
   [(set_attr "type" "load")
@@ -5454,9 +5454,9 @@ archs4x, archs4xd"
 	     (match_operand:SI 3 "const_int_operand" "n,n,n"))]
   "TARGET_HS"
   {
-   if (INTVAL (operands[2]))
+    if ((INTVAL (operands[2]) & 1) != 0)
       return "prefetchw\\t[%0, %1]";
-   else
+    else
       return "prefetch\\t[%0, %1]";
   }
   [(set_attr "type" "load")
@@ -5468,10 +5468,10 @@ archs4x, archs4xd"
 	     (match_operand:SI 2 "const_int_operand" "n"))]
   "TARGET_HS"
   {
-   operands[0] = gen_rtx_MEM (SImode, operands[0]);
-   if (INTVAL (operands[1]))
+    operands[0] = gen_rtx_MEM (SImode, operands[0]);
+    if ((INTVAL (operands[1]) & 1) != 0)
       return "prefetchw%U0\\t%0";
-   else
+    else
       return "prefetch%U0\\t%0";
    }
   [(set_attr "type" "load")