From: Robin Dapp <rdapp@ventanamicro.com>
Date: Fri, 7 Feb 2025 14:42:28 +0000 (+0100)
Subject: RISC-V: Fix some dynamic LMUL costing.
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1eb30ea5e36a0cf01e356337f5fabcd3e05fd373;p=thirdparty%2Fgcc.git

RISC-V: Fix some dynamic LMUL costing.

With all-SLP we annotate statements slightly differently.  This patch
uses STMT_VINFO_RELEVANT_P in order to walk through potential program
points.

Also it makes the LMUL estimate always use the same path.  This helps
fix a number of test cases that regressed since GCC 14.

There are still some failing ones but it appears to me that the chosen
LMUL is still correct and we just expect different log messages.

gcc/ChangeLog:

	* config/riscv/riscv-vector-costs.cc (compute_estimated_lmul):
	Always use vect_vf_for_cost and TARGET_MIN_VLEN.

gcc/testsuite/ChangeLog:

	* gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul4-3.c: Adjust
	expectations.
	* gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul8-9.c: Ditto.
---

diff --git a/gcc/config/riscv/riscv-vector-costs.cc b/gcc/config/riscv/riscv-vector-costs.cc
index c28eecd1110..a39b611e4ce 100644
--- a/gcc/config/riscv/riscv-vector-costs.cc
+++ b/gcc/config/riscv/riscv-vector-costs.cc
@@ -205,9 +205,7 @@ compute_local_program_points (
 	      if (!is_gimple_assign_or_call (gsi_stmt (si)))
 		continue;
 	      stmt_vec_info stmt_info = vinfo->lookup_stmt (gsi_stmt (si));
-	      enum stmt_vec_info_type type
-		= STMT_VINFO_TYPE (vect_stmt_to_vectorize (stmt_info));
-	      if (type != undef_vec_info_type)
+	      if (STMT_VINFO_RELEVANT_P (stmt_info))
 		{
 		  stmt_point info = {point, gsi_stmt (si), stmt_info};
 		  program_points.safe_push (info);
@@ -626,7 +624,7 @@ compute_estimated_lmul (loop_vec_info loop_vinfo, machine_mode mode)
   int regno_alignment = riscv_get_v_regno_alignment (loop_vinfo->vector_mode);
   if (riscv_v_ext_vls_mode_p (loop_vinfo->vector_mode))
     return regno_alignment;
-  else if (known_eq (LOOP_VINFO_SLP_UNROLLING_FACTOR (loop_vinfo), 1U))
+  else
     {
       int estimated_vf = vect_vf_for_cost (loop_vinfo);
       int estimated_lmul = estimated_vf * GET_MODE_BITSIZE (mode).to_constant ()
@@ -636,25 +634,6 @@ compute_estimated_lmul (loop_vec_info loop_vinfo, machine_mode mode)
       else
 	return estimated_lmul;
     }
-  else
-    {
-      /* Estimate the VLA SLP LMUL.  */
-      if (regno_alignment > RVV_M1)
-	return regno_alignment;
-      else if (mode != QImode
-	       || LOOP_VINFO_SLP_UNROLLING_FACTOR (loop_vinfo).is_constant ())
-	{
-	  int ratio;
-	  if (can_div_trunc_p (BYTES_PER_RISCV_VECTOR,
-			       GET_MODE_SIZE (loop_vinfo->vector_mode), &ratio))
-	    {
-	      if (ratio == 1)
-		return RVV_M4;
-	      else if (ratio == 2)
-		return RVV_M2;
-	    }
-	}
-    }
   return 0;
 }
 
diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul4-3.c b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul4-3.c
index 85e3021f1c2..b5a7f180228 100644
--- a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul4-3.c
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul4-3.c
@@ -45,4 +45,4 @@ void foo2 (int64_t *__restrict a,
 /* { dg-final { scan-tree-dump-not "Preferring smaller LMUL loop because it has unexpected spills" "vect" } } */
 /* { dg-final { scan-tree-dump-times "Maximum lmul = 8" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Maximum lmul = 4" 1 "vect" } } */
-/* { dg-final { scan-tree-dump-times "Maximum lmul = 2" 1 "vect" } } */
+/* { dg-final { scan-tree-dump-times "Maximum lmul = 2" 3 "vect" } } */
diff --git a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul8-9.c b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul8-9.c
index 793d16418bf..56234580fa8 100644
--- a/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul8-9.c
+++ b/gcc/testsuite/gcc.dg/vect/costmodel/riscv/rvv/dynamic-lmul8-9.c
@@ -14,6 +14,5 @@ foo (int64_t *__restrict a, int64_t init, int n)
 /* { dg-final { scan-assembler {e64,m8} } } */
 /* { dg-final { scan-assembler-not {csrr} } } */
 /* { dg-final { scan-tree-dump-not "Preferring smaller LMUL loop because it has unexpected spills" "vect" } } */
-/* { dg-final { scan-tree-dump-times "Maximum lmul = 8" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Maximum lmul = 4" 1 "vect" } } */
 /* { dg-final { scan-tree-dump-times "Maximum lmul = 2" 1 "vect" } } */