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From: Richard Biener <>
Subject: [PATCH 1/3] Hide and refactor IVOPTs strip_offset
Date: Wed, 21 Jun 2023 11:30:54 +0000 (UTC)	[thread overview]
Message-ID: <20230621113054.EyBcw1K5C4sJErrT7LBmFHDkCYGqzOZtKrGIMufeROk@z> (raw)

PR110243 shows strip_offset has some correctness issues, the following
avoids using it from loop distribution which can use the more correct
split_constant_offset from data-ref analysis instead.  The patch then
un-exports the function and refactors it to make it obvious the
actual constant offset is only interesting in address-cases.

The series is split, removing one strip_offset at a time for easier
bisecting of code generation quality issues.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

	* (classify_builtin_st): Use
	* tree-ssa-loop-ivopts.h (strip_offset): Remove.
	* (strip_offset): Make static.
	Refactor to make the offset operand optional and assert
	we are dealing with addresses if its required.
 gcc/ |  9 +++++----
 gcc/   | 22 ++++++++++++++--------
 gcc/tree-ssa-loop-ivopts.h    |  1 -
 3 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/gcc/ b/gcc/
index 6291f941a21..cf7c197aaf7 100644
--- a/gcc/
+++ b/gcc/
@@ -1756,11 +1756,12 @@ classify_builtin_st (loop_p loop, partition *partition, data_reference_p dr)
-  poly_uint64 base_offset;
-  unsigned HOST_WIDE_INT const_base_offset;
-  tree base_base = strip_offset (base, &base_offset);
-  if (!base_offset.is_constant (&const_base_offset))
+  tree base_offset;
+  tree base_base;
+  split_constant_offset (base, &base_base, &base_offset);
+  if (!cst_and_fits_in_hwi (base_offset))
+  unsigned HOST_WIDE_INT const_base_offset = int_cst_value (base_offset);
   struct builtin_info *builtin;
   builtin = alloc_builtin (dr, NULL, base, NULL_TREE, size);
diff --git a/gcc/ b/gcc/
index 6fbd2d59318..7978c80b39e 100644
--- a/gcc/
+++ b/gcc/
@@ -1175,6 +1175,9 @@ contain_complex_addr_expr (tree expr)
   return res;
+static tree
+strip_offset (tree expr, poly_uint64_pod *offset = nullptr);
 /* Allocates an induction variable with given initial value BASE and step STEP
    for loop LOOP.  NO_OVERFLOW implies the iv doesn't overflow.  */
@@ -2942,12 +2945,16 @@ strip_offset_1 (tree expr, bool inside_addr, bool top_compref,
 /* Strips constant offsets from EXPR and stores them to OFFSET.  */
+static tree
 strip_offset (tree expr, poly_uint64_pod *offset)
   poly_int64 off;
   tree core = strip_offset_1 (expr, false, false, &off);
-  *offset = off;
+  if (offset)
+    {
+      gcc_assert (POINTER_TYPE_P (expr));
+      *offset = off;
+    }
   return core;
@@ -3512,7 +3519,6 @@ add_iv_candidate_derived_from_uses (struct ivopts_data *data)
 static void
 add_iv_candidate_for_use (struct ivopts_data *data, struct iv_use *use)
-  poly_uint64 offset;
   tree base;
   struct iv *iv = use->iv;
   tree basetype = TREE_TYPE (iv->base);
@@ -3563,8 +3569,8 @@ add_iv_candidate_for_use (struct ivopts_data *data, struct iv_use *use)
   /* Record common candidate with constant offset stripped in base.
      Like the use itself, we also add candidate directly for it.  */
-  base = strip_offset (iv->base, &offset);
-  if (maybe_ne (offset, 0U) || base != iv->base)
+  base = strip_offset (iv->base);
+  if (base != iv->base)
       record_common_cand (data, base, iv->step, use);
       add_candidate (data, base, iv->step, false, use);
@@ -3582,9 +3588,9 @@ add_iv_candidate_for_use (struct ivopts_data *data, struct iv_use *use)
       step = fold_convert (sizetype, step);
       record_common_cand (data, base, step, use);
       /* Also record common candidate with offset stripped.  */
-      base = strip_offset (base, &offset);
-      if (maybe_ne (offset, 0U))
-	record_common_cand (data, base, step, use);
+      tree alt_base = strip_offset (base);
+      if (alt_base != base)
+	record_common_cand (data, alt_base, step, use);
   /* At last, add auto-incremental candidates.  Make such variables
diff --git a/gcc/tree-ssa-loop-ivopts.h b/gcc/tree-ssa-loop-ivopts.h
index 95148616e70..7a53ce47f10 100644
--- a/gcc/tree-ssa-loop-ivopts.h
+++ b/gcc/tree-ssa-loop-ivopts.h
@@ -28,7 +28,6 @@ extern void dump_cand (FILE *, struct iv_cand *);
 extern bool contains_abnormal_ssa_name_p (tree);
 extern class loop *outermost_invariant_loop_for_expr (class loop *, tree);
 extern bool expr_invariant_in_loop_p (class loop *, tree);
-extern tree strip_offset (tree, poly_uint64_pod *);
 bool may_be_nonaddressable_p (tree expr);
 void tree_ssa_iv_optimize (void);

             reply	other threads:[~2023-06-21 11:30 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-21 11:30 Richard Biener [this message]
2023-06-21 11:43 Richard Biener

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