[gcc(refs/vendors/riscv/heads/gcc-14-with-riscv-opts)] [to-be-committed][RISC-V][PR target/115142] Do not create invalidate shift-add insn

[Jeff Law <law@gcc.gnu.org>]

https://gcc.gnu.org/g:58349b4561b0cc315e60ff5aa2b777a3e80c7f9f

commit 58349b4561b0cc315e60ff5aa2b777a3e80c7f9f
Author: Jeff Law <jlaw@ventanamicro.com>
Date:   Sun May 19 09:56:16 2024 -0600

    [to-be-committed][RISC-V][PR target/115142] Do not create invalidate shift-add insn
    
    The circumstances which triggered this weren't something that should appear in
    the wild (-ftree-ter, without optimization enabled).  So I wasn't planning to
    backport.  Obviously if it shows up in another context we can revisit that
    decision.
    
    I've run this through my rv32gcv and rv64gc tester.  Waiting on the CI system before committing.
    
            PR target/115142
    gcc/
    
            * config/riscv/riscv.cc (mem_shadd_or_shadd_rtx_p): Make sure
            shifted argument is a register.
    
    gcc/testsuite
    
            * gcc.target/riscv/pr115142.c: New test.
    
    (cherry picked from commit e1ce9c37ed68136a99d44c8301990c184ba41849)

Diff:
---
 gcc/config/riscv/riscv.cc                 |  1 +
 gcc/testsuite/gcc.target/riscv/pr115142.c | 10 ++++++++++
 2 files changed, 11 insertions(+)

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 7a34b4be873..d0c22058b8c 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -2465,6 +2465,7 @@ mem_shadd_or_shadd_rtx_p (rtx x)
 {
   return ((GET_CODE (x) == ASHIFT
 	   || GET_CODE (x) == MULT)
+	  && register_operand (XEXP (x, 0), GET_MODE (x))
 	  && CONST_INT_P (XEXP (x, 1))
 	  && ((GET_CODE (x) == ASHIFT && IN_RANGE (INTVAL (XEXP (x, 1)), 1, 3))
 	      || (GET_CODE (x) == MULT
diff --git a/gcc/testsuite/gcc.target/riscv/pr115142.c b/gcc/testsuite/gcc.target/riscv/pr115142.c
new file mode 100644
index 00000000000..40ba49dfa20
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/pr115142.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O0 -ftree-ter" } */
+
+long a;
+char b;
+void e() {
+  char f[8][1];
+  b = f[a][a];
+}
+