[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:9e17aea0b8a6e0a620533645a2024ab0c03f9063

commit 9e17aea0b8a6e0a620533645a2024ab0c03f9063
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 e33a05cf96d..cea7a76ab1f 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -2476,6 +2476,7 @@ 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];
+}
+