From: Keith Packard <keithp@keithp.com>
Date: Sat, 15 Feb 2025 16:17:41 +0000 (-0700)
Subject: [PATCH] rx: allow cmpstrnsi len to be zero
X-Git-Tag: basepoints/gcc-16~1986
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=11cc336eed42892b7cfc2bfcf7b3f3f86f61787a;p=thirdparty%2Fgcc.git

[PATCH] rx: allow cmpstrnsi len to be zero

The SCMPU instruction doesn't change the C and Z flags when the
incoming length is zero, which means the insn will produce a
value based upon the existing flag values.

As a quick kludge, adjust these flags to ensure a zero result in this
case.

gcc/
	* config/rx/rx.md (rx_cmpstrn): Correctly handle len=0 case.
---

diff --git a/gcc/config/rx/rx.md b/gcc/config/rx/rx.md
index 89211585c9c..edb2c96603f 100644
--- a/gcc/config/rx/rx.md
+++ b/gcc/config/rx/rx.md
@@ -2590,7 +2590,9 @@
    (clobber (reg:SI 3))
    (clobber (reg:CC CC_REG))]
   "rx_allow_string_insns"
-  "scmpu		; Perform the string comparison
+  "setpsw  z		; Set flags in case len is zero
+   setpsw  c
+   scmpu		; Perform the string comparison
    mov     #-1, %0      ; Set up -1 result (which cannot be created
                         ; by the SC insn)
    bnc	   ?+		; If Carry is not set skip over