It turns out easy to add support for memcpy copy prop when the memcpy
has changed into `MEM<char[N]>` copy.
Instead of rejecting right out we need to figure out that
`a` and `MEM<char[N]>[&a]` are equivalent in terms of address and size.
And then create a VIEW_CONVER_EXPR from the original src to the new type.
Note this also allows for `a.b` and `a` being considered equivalent if b is the
only field (PR 121751).
Changes since v1:
* v2: Move check for IMAG/REAL and BFR earlier.
Add a wrapping function around get_inner_reference and use that instead
of get_addr_base_and_unit_offset.
Bootstrapped and tested on x86_64-linux-gnu.
PR tree-optimization/121751
PR tree-optimization/121418
PR tree-optimization/121417
gcc/ChangeLog:
* tree-ssa-forwprop.cc (split_core_and_offset_size): New function.
(optimize_agr_copyprop_1): Allow for the same
address but different type accesses via a VCE.
gcc/testsuite/ChangeLog:
* gcc.dg/tree-ssa/copy-prop-aggregate-1.c: New test.
* gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-1.c: New test.
* gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-2.c: New test.
Signed-off-by: Andrew Pinski <[email protected]>
---
.../gcc.dg/tree-ssa/copy-prop-aggregate-1.c | 33 ++++++
.../tree-ssa/copy-prop-aggregate-memcpy-1.c | 18 ++++
.../tree-ssa/copy-prop-aggregate-memcpy-2.c | 20 ++++
gcc/tree-ssa-forwprop.cc | 100 +++++++++++++++++-
4 files changed, 170 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-1.c
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-1.c
create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-2.c
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-1.c
b/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-1.c
new file mode 100644
index 00000000000..1094c4d768b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-1.c
@@ -0,0 +1,33 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-forwprop1-details -fdump-tree-optimized" } */
+/* PR tree-optimization/121751 */
+
+
+struct s1
+{
+ int t[1024];
+};
+
+struct s2 {
+ struct s1 t;
+};
+
+struct s3
+{
+ struct s2 t;
+};
+
+void g(struct s3*);
+
+void f(struct s1 s)
+{
+ struct s2 removeme;
+ removeme.t = s;
+ struct s3 t1;
+ t1.t = removeme;
+ g(&t1);
+}
+
+
+/* { dg-final { scan-tree-dump-times "after previous" 1 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-not "removeme " "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-1.c
b/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-1.c
new file mode 100644
index 00000000000..5faf6d0bf9b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-1.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-forwprop1-details -fdump-tree-optimized" } */
+/* PR tree-optimization/121418 */
+
+struct s1
+{
+ unsigned char t[1024];
+};
+
+struct s1 f(struct s1 a)
+{
+ struct s1 removeme1 = a;
+ __builtin_memcpy (&removeme1, &a, sizeof(struct s1));
+ return removeme1;
+}
+
+/* { dg-final { scan-tree-dump-times "after previous" 1 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-not "removeme1 " "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-2.c
b/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-2.c
new file mode 100644
index 00000000000..b1ba30d0aba
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/copy-prop-aggregate-memcpy-2.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O1 -fdump-tree-forwprop1-details -fdump-tree-optimized" } */
+/* PR tree-optimization/121417 */
+
+struct s1
+{
+ unsigned char t[1024];
+};
+
+struct s1 f(struct s1 a)
+{
+ struct s1 removeme1 = a;
+ struct s1 removeme2;
+ __builtin_memcpy (&removeme2, &removeme1, sizeof(struct s1));
+ return removeme2;
+}
+
+/* { dg-final { scan-tree-dump-times "after previous" 2 "forwprop1" } } */
+/* { dg-final { scan-tree-dump-not "removeme1 " "optimized" } } */
+/* { dg-final { scan-tree-dump-not "removeme2 " "optimized" } } */
diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
index 9c6f4b355d6..1eacff01587 100644
--- a/gcc/tree-ssa-forwprop.cc
+++ b/gcc/tree-ssa-forwprop.cc
@@ -1418,6 +1418,46 @@ optimize_aggr_zeroprop (gimple_stmt_iterator *gsip, bool
full_walk)
return changed;
}
+/* Returns the pointer to the base of the object of the
+ reference EXPR and extracts the information about
+ the offset of the access, storing it to PBYTESIZE,
+ PBYTEPOS and PREVERSEP.
+ If the access is not a byte sized or position is not
+ on the byte, return NULL. */
+static tree
+split_core_and_offset_size (tree expr,
+ poly_int64 *pbytesize, poly_int64 *pbytepos,
+ tree *poffset, int *preversep)
+{
+ tree core;
+ machine_mode mode;
+ int unsignedp, volatilep;
+ poly_int64 bitsize;
+ poly_int64 bitpos;
+ location_t loc = EXPR_LOCATION (expr);
+
+ core = get_inner_reference (expr, &bitsize, &bitpos,
+ poffset, &mode, &unsignedp, preversep,
+ &volatilep);
+ if (!multiple_p (bitsize, BITS_PER_UNIT, pbytesize))
+ return NULL_TREE;
+ if (!multiple_p (bitpos, BITS_PER_UNIT, pbytepos))
+ return NULL_TREE;
+ /* If we are left with MEM[a + CST] strip that and add it to the
+ pbytepos and return a. */
+ if (TREE_CODE (core) == MEM_REF)
+ {
+ poly_offset_int tem;
+ tem = wi::to_poly_offset (TREE_OPERAND (core, 1));
+ tem += *pbytepos;
+ if (tem.to_shwi (pbytepos))
+ return TREE_OPERAND (core, 0);
+ }
+ core = build_fold_addr_expr_loc (loc, core);
+ STRIP_NOPS (core);
+ return core;
+}
+
/* Helper function for optimize_agr_copyprop.
For aggregate copies in USE_STMT, see if DEST
is on the lhs of USE_STMT and replace it with SRC. */
@@ -1434,8 +1474,66 @@ optimize_agr_copyprop_1 (gimple *stmt, gimple *use_stmt,
/* If the new store is `src2 = src2;` skip over it. */
if (operand_equal_p (src2, dest2, 0))
return false;
+ /* If the second src is not exactly the same as dest,
+ try to handle it seperately; see it is address/size equivalent.
+ Handles `a` and `a.b` and `MEM<char[N]>(&a)` which all have
+ the same size and offsets as address/size equivalent.
+ This allows copying over a memcpy and also one for copying
+ where one field is the same size as the whole struct. */
if (!operand_equal_p (dest, src2, 0))
- return false;
+ {
+ /* A VCE can't be used with imag/real or BFR so reject them early. */
+ if (TREE_CODE (src) == IMAGPART_EXPR
+ || TREE_CODE (src) == REALPART_EXPR
+ || TREE_CODE (src) == BIT_FIELD_REF)
+ return false;
+ tree core1, core2;
+ poly_int64 bytepos1, bytepos2;
+ poly_int64 bytesize1, bytesize2;
+ tree toffset1, toffset2;
+ int reversep1 = 0;
+ int reversep2 = 0;
+ poly_int64 diff = 0;
+ core1 = split_core_and_offset_size (dest, &bytesize1, &bytepos1,
+ &toffset1, &reversep1);
+ core2 = split_core_and_offset_size (src2, &bytesize2, &bytepos2,
+ &toffset2, &reversep2);
+ if (!core1 || !core2)
+ return false;
+ if (reversep1 != reversep2)
+ return false;
+ /* The sizes of the 2 accesses need to be the same. */
+ if (!known_eq (bytesize1, bytesize2))
+ return false;
+ if (!operand_equal_p (core1, core2, 0))
+ return false;
+
+ if (toffset1 && toffset2)
+ {
+ tree type = TREE_TYPE (toffset1);
+ if (type != TREE_TYPE (toffset2))
+ toffset2 = fold_convert (type, toffset2);
+
+ tree tdiff = fold_build2 (MINUS_EXPR, type, toffset1, toffset2);
+ if (!cst_and_fits_in_hwi (tdiff))
+ return false;
+
+ diff = int_cst_value (tdiff);
+ }
+ else if (toffset1 || toffset2)
+ {
+ /* If only one of the offsets is non-constant, the difference cannot
+ be a constant. */
+ return false;
+ }
+ diff += bytepos1 - bytepos2;
+ /* The offset between the 2 need to be 0. */
+ if (!known_eq (diff, 0))
+ return false;
+ src = fold_build1_loc (gimple_location (use_stmt),
+ VIEW_CONVERT_EXPR,
+ TREE_TYPE (src2), src);
+ }
/* For 2 memory refences and using a temporary to do the copy,
don't remove the temporary as the 2 memory references might overlap.
Note t does not need to be decl as it could be field.
--
2.43.0
