[committed][RISC-V] Add testcase for shifted truthvalue

[Jeff Law]

I was doing some cleanup on our internal tree and noticed a pattern that 
I didn't think was actually useful in practice.  Thankfully the internal 
commit included a testcase clearly targeting that pattern.

I'm upstreaming the testcase, but not the unnecessary pattern.
Jeff

commit 191896c993b1ba23dba0d0babbf8d1a043de2bd3
Author: Philipp Tomsich <philipp.toms...@vrull.eu>
Date:   Sat Nov 8 09:28:07 2025 -0700

    [RISC-V] Add testcase for shifted truthvalue
    
    I was doing some cleanup on our internal tree and noticed a pattern that I
    didn't think was actually useful in practice.  Thankfully the internal 
commit
    included a testcase clearly targeting that pattern.
    
    I'm upstreaming the testcase, but not the unnecessary pattern.
    
    gcc/testsuite
            * gcc.target/riscv/snez.c: New test.

diff --git a/gcc/testsuite/gcc.target/riscv/snez.c 
b/gcc/testsuite/gcc.target/riscv/snez.c
new file mode 100644
index 000000000000..e5a7fad770a0
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/snez.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc -mabi=lp64" } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Og" "-O1" } } */
+
+int f (long long a)
+{
+  return (a != 2) << 1;
+}
+
+/* { dg-final { scan-assembler-times "slli\t" 1 } } */
+/* { dg-final { scan-assembler-not "srli\t" } } */
+/* { dg-final { scan-assembler-times "snez\t" 1 } } */
+/* { dg-final { scan-assembler-not "sext.w\t" } } */
+