From: Robin Dapp <rdapp@oss.qualcomm.com>
Date: Mon, 2 Feb 2026 09:28:08 +0000 (+0100)
Subject: RISC-V: Disable small memsets for xtheadvector [PR123910].
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c3e3456007a46f5eb790817631a656a963326ddf;p=thirdparty%2Fgcc.git

RISC-V: Disable small memsets for xtheadvector [PR123910].

This patch disables memsets with size less than a vector for
xtheadvector.  As xtheadvector does not support fractional
LMUL we need to ensure to not emit those vectors that might
use it.

	PR target/123910

gcc/ChangeLog:

	* config/riscv/riscv-string.cc (riscv_expand_block_move):
	Remove !xtheadvector guard.
	(use_vector_stringop_p): Guard small LMULs.
	(check_vectorise_memory_operation): Ditto.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/pr123910.c: New test.
	* gcc.target/riscv/rvv/xtheadvector/pr114194-rv32.c: xfail.

Signed-off-by: Robin Dapp <rdapp@oss.qualcomm.com>
---

diff --git a/gcc/config/riscv/riscv-string.cc b/gcc/config/riscv/riscv-string.cc
index ad71a103edc..51b98e4906c 100644
--- a/gcc/config/riscv/riscv-string.cc
+++ b/gcc/config/riscv/riscv-string.cc
@@ -980,7 +980,7 @@ riscv_expand_block_move_scalar (rtx dest, rtx src, rtx length)
 bool
 riscv_expand_block_move (rtx dest, rtx src, rtx length)
 {
-  if ((TARGET_VECTOR && !TARGET_XTHEADVECTOR)
+  if (TARGET_VECTOR
       && stringop_strategy & STRATEGY_VECTOR)
     {
       bool ok = riscv_vector::expand_block_move (dest, src, length, false);
@@ -1086,9 +1086,15 @@ use_vector_stringop_p (struct stringop_info &info, HOST_WIDE_INT max_ew,
   rtx avl = length_in;
   HOST_WIDE_INT potential_ew = max_ew;
 
-  if (!TARGET_VECTOR || !(stringop_strategy & STRATEGY_VECTOR))
+  if (!TARGET_VECTOR
+      || !(stringop_strategy & STRATEGY_VECTOR))
     return false;
 
+  if (TARGET_XTHEADVECTOR
+      && (!CONST_INT_P (length_in)
+	  || known_lt (INTVAL (length_in), BYTES_PER_RISCV_VECTOR)))
+      return false;
+
   int max_lmul = TARGET_MAX_LMUL;
   if (rvv_max_lmul == RVV_CONV_DYNAMIC)
     max_lmul = RVV_M1;
@@ -1598,6 +1604,10 @@ check_vectorise_memory_operation (rtx length_in, HOST_WIDE_INT &lmul_out)
 
   HOST_WIDE_INT length = INTVAL (length_in);
 
+  if (TARGET_XTHEADVECTOR
+      && known_lt (length, BYTES_PER_RISCV_VECTOR))
+    return false;
+
   /* If it's tiny, default operation is likely better; maybe worth
      considering fractional lmul in the future as well.  */
   if (length < (TARGET_MIN_VLEN / 8))
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123910.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123910.c
new file mode 100644
index 00000000000..a38dbb5fa5c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr123910.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-mcpu=xt-c920 -mrvv-vector-bits=zvl" } */
+
+int i;
+void *p;
+
+void
+foo ()
+{
+  __builtin_memset (p, i, 8);
+}
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr114194-rv32.c b/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr114194-rv32.c
index f95e713ea24..a9766ddffcb 100644
--- a/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr114194-rv32.c
+++ b/gcc/testsuite/gcc.target/riscv/rvv/xtheadvector/pr114194-rv32.c
@@ -1,5 +1,5 @@
-/* { dg-do compile { target { { ! riscv_abi_e } && rv32 } } } */
-/* { dg-options "-march=rv32gc_xtheadvector -O2" } */
+/* { dg-do compile { target { ! riscv_abi_e } } } */
+/* { dg-options "-march=rv32gc_xtheadvector -O2 -mabi=ilp32d " } */
 /* { dg-final { check-function-bodies "**" "" } } */
 
 /*
@@ -13,7 +13,7 @@ void foo0_1 (void *p)
 }
 
 /*
-** foo0_7:
+** foo0_7: { xfail *-*-* }
 **	li\t[a-x0-9]+,7
 **	th.vsetvli\tzero,[a-x0-9]+,e8,m1
 **	th\.vmv\.v\.i\tv[0-9],0
@@ -37,7 +37,7 @@ void foo1_1 (void *p)
 }
 
 /*
-** foo1_5:
+** foo1_5: { xfail *-*-* }
 **	li\t[a-x0-9]+,5
 **	th.vsetvli\tzero,[a-x0-9]+,e8,m1
 **	th\.vmv\.v\.i\tv[0-9],1