[gcc r15-4378] RISC-V: Use biggest_mode as mode for constants.

[Robin Dapp via Gcc-cvs]

https://gcc.gnu.org/g:cc217a1ecb04c9234b2cce7ba3c27701a050e402

commit r15-4378-gcc217a1ecb04c9234b2cce7ba3c27701a050e402
Author: Robin Dapp <rd...@ventanamicro.com>
Date:   Tue Oct 15 12:10:48 2024 +0200

    RISC-V: Use biggest_mode as mode for constants.
    
    In compute_nregs_for_mode we expect that the current variable's mode is
    at most as large as the biggest mode to be used for vectorization.
    
    This might not be true for constants as they don't actually have a mode.
    In that case, just use the biggest mode so max_number_of_live_regs
    returns 1.
    
    This fixes several test cases in the test suite.
    
    gcc/ChangeLog:
    
            PR target/116655
    
            * config/riscv/riscv-vector-costs.cc (max_number_of_live_regs):
            Use biggest mode instead of constant's saved mode.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/riscv/rvv/autovec/pr116655.c: New test.

Diff:
---
 gcc/config/riscv/riscv-vector-costs.cc                | 14 ++++++++++----
 gcc/testsuite/gcc.target/riscv/rvv/autovec/pr116655.c | 11 +++++++++++
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/gcc/config/riscv/riscv-vector-costs.cc 
b/gcc/config/riscv/riscv-vector-costs.cc
index 25570bd40040..67b9e3e8f413 100644
--- a/gcc/config/riscv/riscv-vector-costs.cc
+++ b/gcc/config/riscv/riscv-vector-costs.cc
@@ -194,7 +194,7 @@ compute_local_program_points (
       /* Collect the stmts that is vectorized and mark their program point.  */
       for (i = 0; i < nbbs; i++)
        {
-         int point = 1;
+         unsigned int point = 1;
          basic_block bb = bbs[i];
          vec<stmt_point> program_points = vNULL;
          if (dump_enabled_p ())
@@ -489,9 +489,15 @@ max_number_of_live_regs (loop_vec_info loop_vinfo, const 
basic_block bb,
       pair live_range = (*iter).second;
       for (i = live_range.first + 1; i <= live_range.second; i++)
        {
-         machine_mode mode = TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE
-                               ? BImode
-                               : TYPE_MODE (TREE_TYPE (var));
+         machine_mode mode;
+         if (TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE)
+           mode = BImode;
+         /* Constants do not have a mode, just use the biggest so
+            compute_nregs will return 1.  */
+         else if (TREE_CODE (var) == INTEGER_CST)
+           mode = biggest_mode;
+         else
+           mode = TYPE_MODE (TREE_TYPE (var));
          unsigned int nregs
            = compute_nregs_for_mode (loop_vinfo, mode, biggest_mode, lmul);
          live_vars_vec[i] += nregs;
diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr116655.c 
b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr116655.c
new file mode 100644
index 000000000000..36768e37d005
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr116655.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -march=rv64imv -mabi=lp64d -mrvv-max-lmul=dynamic" } */
+
+short a[5];
+int b() {
+  int c = 0;
+  for (; c <= 4; c++)
+    if (a[c])
+      break;
+  return c;
+}