[gcc r14-4607] RISC-V: Fix the riscv_legitimize_poly_move issue on targets where the minimal VLEN exceeds 512.

[Kito Cheng <kito@gcc.gnu.org>]

https://gcc.gnu.org/g:0f40e59f193f96f1bb0fa3e1c2d160567ed29b32

commit r14-4607-g0f40e59f193f96f1bb0fa3e1c2d160567ed29b32
Author: Kito Cheng <kito.cheng@sifive.com>
Date:   Tue Oct 3 10:27:24 2023 +0800

    RISC-V: Fix the riscv_legitimize_poly_move issue on targets where the minimal VLEN exceeds 512.
    
    riscv_legitimize_poly_move was expected to ensure the poly value is at most 32
    times smaller than the minimal VLEN (32 being derived from '4096 / 128').
    This assumption held when our mode modeling was not so precisely defined.
    However, now that we have modeled the mode size according to the correct minimal
    VLEN info, the size difference between different RVV modes can be up to 64
    times. For instance, comparing RVVMF64BI and RVVMF1BI, the sizes are [1, 1]
    versus [64, 64] respectively.
    
    gcc/ChangeLog:
    
            * config/riscv/riscv.cc (riscv_legitimize_poly_move): Bump
            max_power to 64.
            * config/riscv/riscv.h (MAX_POLY_VARIANT): New.
    
    gcc/testsuite/ChangeLog:
    
            * g++.target/riscv/rvv/autovec/bug-01.C: New.
            * g++.target/riscv/rvv/rvv.exp: Add autovec folder.

Diff:
---
 gcc/config/riscv/riscv.cc                          |  5 ++--
 gcc/config/riscv/riscv.h                           |  5 ++++
 .../g++.target/riscv/rvv/autovec/bug-01.C          | 33 ++++++++++++++++++++++
 gcc/testsuite/g++.target/riscv/rvv/rvv.exp         |  3 ++
 4 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index 66a55a73cb5..44746256f61 100644
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -2404,9 +2404,8 @@ riscv_legitimize_poly_move (machine_mode mode, rtx dest, rtx tmp, rtx src)
     }
   else
     {
-      /* FIXME: We currently DON'T support TARGET_MIN_VLEN > 4096.  */
-      int max_power = exact_log2 (4096 / 128);
-      for (int i = 0; i < max_power; i++)
+      int max_power = exact_log2 (MAX_POLY_VARIANT);
+      for (int i = 0; i <= max_power; i++)
 	{
 	  int possible_div_factor = 1 << i;
 	  if (factor % (vlenb / possible_div_factor) == 0)
diff --git a/gcc/config/riscv/riscv.h b/gcc/config/riscv/riscv.h
index f43ff10bc83..01645141935 100644
--- a/gcc/config/riscv/riscv.h
+++ b/gcc/config/riscv/riscv.h
@@ -1191,4 +1191,9 @@ extern void riscv_remove_unneeded_save_restore_calls (void);
 #define OPTIMIZE_MODE_SWITCHING(ENTITY) (TARGET_VECTOR)
 #define NUM_MODES_FOR_MODE_SWITCHING {VXRM_MODE_NONE, riscv_vector::FRM_NONE}
 
+
+/* The size difference between different RVV modes can be up to 64 times.
+   e.g. RVVMF64BI vs RVVMF1BI on zvl512b, which is [1, 1] vs [64, 64].  */
+#define MAX_POLY_VARIANT 64
+
 #endif /* ! GCC_RISCV_H */
diff --git a/gcc/testsuite/g++.target/riscv/rvv/autovec/bug-01.C b/gcc/testsuite/g++.target/riscv/rvv/autovec/bug-01.C
new file mode 100644
index 00000000000..fd10009ddbe
--- /dev/null
+++ b/gcc/testsuite/g++.target/riscv/rvv/autovec/bug-01.C
@@ -0,0 +1,33 @@
+/* { dg-options "-march=rv64gcv_zvl512b -mabi=lp64d -O3" } */
+
+class c {
+public:
+  int e();
+  void j();
+};
+float *d;
+class k {
+  int f;
+
+public:
+  k(int m) : f(m) {}
+  float g;
+  float h;
+  void n(int m) {
+    for (int i; i < m; i++) {
+      d[0] = d[1] = d[2] = g;
+      d[3] = h;
+      d += f;
+    }
+  }
+};
+c l;
+void o() {
+  int b = l.e();
+  k a(b);
+  for (;;)
+    if (b == 4) {
+      l.j();
+      a.n(2);
+    }
+}
diff --git a/gcc/testsuite/g++.target/riscv/rvv/rvv.exp b/gcc/testsuite/g++.target/riscv/rvv/rvv.exp
index 249530580d7..c30d6e93144 100644
--- a/gcc/testsuite/g++.target/riscv/rvv/rvv.exp
+++ b/gcc/testsuite/g++.target/riscv/rvv/rvv.exp
@@ -40,5 +40,8 @@ set CFLAGS "-march=$gcc_march -O3"
 dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/base/*.C]] \
 	"" $CFLAGS
 
+dg-runtest [lsort [glob -nocomplain $srcdir/$subdir/autovec/*.\[C\]]] \
+        "" $CFLAGS
+
 # All done.
 dg-finish