From: Andrew Pinski <apin...@marvell.com>
These two testcases have been failing since GCC 5 but things
have improved such that adding a simplification to match.pd
for this case is easier than before.
In the end we have the following IR:
....
_5 = &a[1] + _4;
_7 = &a + _13;
if (_5 != _7)
So we can fold the _5 != _7 into:
(&a[1] - &a) + _4 != _13
The subtraction is folded into constant by ptr_difference_const.
In this case, the full expression gets folded into a constant
and we are able to remove the if statement.
OK? Bootstrapped and tested on aarch64-linux-gnu with no regressions.
gcc/ChangeLog:
* match.pd: Add simplification of pointer_diff of two pointer_plus
with addr_expr in the first operand of each pointer_plus.
Add simplificatoin of ne/eq of two pointer_plus with addr_expr
in the first operand of each pointer_plus.
gcc/testsuite/ChangeLog:
* c-c++-common/pr19807-2.c: Enable for all targets and remove the xfail.
* c-c++-common/pr19807-3.c: Likewise.
---
gcc/match.pd | 15 +++++++++++++++
gcc/testsuite/c-c++-common/pr19807-2.c | 5 ++---
gcc/testsuite/c-c++-common/pr19807-3.c | 5 ++---
3 files changed, 19 insertions(+), 6 deletions(-)
diff --git a/gcc/match.pd b/gcc/match.pd
index f920bc4b7c1..cc7809dfe0f 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -2063,6 +2063,21 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(if (ptr_difference_const (@0, @1, &diff))
{ build_int_cst_type (type, diff); }))))
+/* (&a+b) - (&a[1] + c) -> sizeof(a[0]) + (b - c) */
+(simplify
+ (pointer_diff (pointer_plus ADDR_EXPR@0 @1) (pointer_plus ADDR_EXPR@2 @3))
+ (with { poly_int64 diff; }
+ (if (ptr_difference_const (@0, @2, &diff))
+ (plus { build_int_cst_type (type, diff); } (convert (minus @1 @3))))))
+
+/* (&a+b) !=/== (&a[1] + c) -> sizeof(a[0]) + b !=/== c */
+(for neeq (ne eq)
+ (simplify
+ (neeq (pointer_plus ADDR_EXPR@0 @1) (pointer_plus ADDR_EXPR@2 @3))
+ (with { poly_int64 diff; tree inner_type = TREE_TYPE (@1);}
+ (if (ptr_difference_const (@0, @2, &diff))
+ (neeq (plus { build_int_cst_type (inner_type, diff); } @1) @3)))))
+
/* Canonicalize (T *)(ptr - ptr-cst) to &MEM[ptr + -ptr-cst]. */
(simplify
(convert (pointer_diff @0 INTEGER_CST@1))
diff --git a/gcc/testsuite/c-c++-common/pr19807-2.c
b/gcc/testsuite/c-c++-common/pr19807-2.c
index d2c010140d0..529b9c97322 100644
--- a/gcc/testsuite/c-c++-common/pr19807-2.c
+++ b/gcc/testsuite/c-c++-common/pr19807-2.c
@@ -1,5 +1,4 @@
-/* Some targets can optimize this on RTL. */
-/* { dg-do link { target { x86_64-*-* i?86-*-* } } } */
+/* { dg-do link } */
/* { dg-options "-O -fdump-tree-optimized" } */
extern void link_error(void);
@@ -12,4 +11,4 @@ int main()
return 0;
}
-/* { dg-final { scan-tree-dump-not "link_error" "optimized" { xfail *-*-* } }
} */
+/* { dg-final { scan-tree-dump-not "link_error" "optimized" } } */
diff --git a/gcc/testsuite/c-c++-common/pr19807-3.c
b/gcc/testsuite/c-c++-common/pr19807-3.c
index bb7f9827725..31c88f3b850 100644
--- a/gcc/testsuite/c-c++-common/pr19807-3.c
+++ b/gcc/testsuite/c-c++-common/pr19807-3.c
@@ -1,5 +1,4 @@
-/* Some targets can optimize this on RTL. */
-/* { dg-do link { target { x86_64-*-* i?86-*-* } } } */
+/* { dg-do link } */
/* { dg-options "-O -fdump-tree-optimized" } */
extern void link_error(void);
@@ -12,4 +11,4 @@ int main()
return 0;
}
-/* { dg-final { scan-tree-dump-not "link_error" "optimized" { xfail *-*-* } }
} */
+/* { dg-final { scan-tree-dump-not "link_error" "optimized" } } */
--
2.17.1
