Drop SSE5 leftovers from both its comment and its default calculation.
A value of 2 simply cannot occur anymore. Instead extend the comment to
mention the use of the attribute in "length_vex", clarifying why
"prefix_extra" can actually be meaningful on VEX-encoded insns despite
those not having any real prefixes except possibly segment overrides.
gcc/
* config/i386/i386.md (prefix_extra): Correct comment. Fold
cases yielding 2 into ones yielding 1.
---
I question the 3DNow! aspect here: There's no extra prefix there. It's
an immediate instead which "sub-divides" major opcode 0f0f.
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -620,13 +620,11 @@
(const_int 0)))
;; There are also additional prefixes in 3DNOW, SSSE3.
-;; ssemuladd,sse4arg default to 0f24/0f25 and DREX byte,
-;; sseiadd1,ssecvt1 to 0f7a with no DREX byte.
;; 3DNOW has 0f0f prefix, SSSE3 and SSE4_{1,2} 0f38/0f3a.
+;; While generally inapplicable to VEX/XOP/EVEX encodings, "length_vex" uses
+;; the attribute evaluating to zero to know that VEX2 encoding may be usable.
(define_attr "prefix_extra" ""
- (cond [(eq_attr "type" "ssemuladd,sse4arg")
- (const_int 2)
- (eq_attr "type" "sseiadd1,ssecvt1")
+ (cond [(eq_attr "type" "ssemuladd,sse4arg,sseiadd1,ssecvt1")
(const_int 1)
]
(const_int 0)))
