From 96fb71883d438bdb241fdf9c7d12f945c5ba0c7f Mon Sep 17 00:00:00 2001
From: Martin Jambor <mjambor@suse.cz>
Date: Tue, 17 Dec 2024 11:17:14 +0100
Subject: [PATCH] ipa: Skip widening type conversions in jump function
constructions
Originally, we did not stream any formal parameter types into WPA and
were generally very conservative when it came to type mismatches in
IPA-CP. Over the time, mismatches that happen in code and blew up in
WPA made us to be much more resilient and also to stream the types of
the parameters which we now use commonly.
With that information, we can safely skip conversions when looking at
the IL from which we build jump functions and then simply fold convert
the constants and ranges to the resulting type, as long as we are
careful that performing the corresponding folding of constants gives
the corresponding results. In order to do that, we must ensure that
the old value can be represented in the new one without any loss.
With this change, we can nicely propagate non-NULLness in IPA-VR as
demonstrated with the new test case.
I have gone through all other uses of (all components of) jump
functions which could be affected by this and verified they do indeed
check types and can handle mismatches.
gcc/ChangeLog:
2024-12-11 Martin Jambor <mjambor@suse.cz>
* ipa-prop.cc: Include vr-values.h.
(skip_a_safe_conversion_op): New function.
(ipa_compute_jump_functions_for_edge): Use it.
gcc/testsuite/ChangeLog:
2024-11-01 Martin Jambor <mjambor@suse.cz>
* gcc.dg/ipa/vrp9.c: New test.
---
gcc/ipa-prop.cc | 40 +++++++++++++++++++++++++++
gcc/testsuite/gcc.dg/ipa/vrp9.c | 48 +++++++++++++++++++++++++++++++++
2 files changed, 88 insertions(+)
create mode 100644 gcc/testsuite/gcc.dg/ipa/vrp9.c
diff --git a/gcc/ipa-prop.cc b/gcc/ipa-prop.cc
index 3d72794e37c4..ae309ec78a2d 100644
--- a/gcc/ipa-prop.cc
+++ b/gcc/ipa-prop.cc
@@ -59,6 +59,7 @@ along with GCC; see the file COPYING3. If not see
#include "attr-fnspec.h"
#include "gimple-range.h"
#include "value-range-storage.h"
+#include "vr-values.h"
/* Function summary where the parameter infos are actually stored. */
ipa_node_params_t *ipa_node_params_sum = NULL;
@@ -2311,6 +2312,44 @@ ipa_set_jfunc_vr (ipa_jump_func *jf, const ipa_vr &vr)
ipa_set_jfunc_vr (jf, tmp);
}
+
+/* If T is an SSA_NAME that is the result of a simple type conversion statement
+ from an integer type to another integer type which is known to be able to
+ represent the values the operand of the conversion can hold, return the
+ operand of that conversion, otherwise return T. */
+
+static tree
+skip_a_safe_conversion_op (tree t)
+{
+ if (TREE_CODE (t) != SSA_NAME
+ || SSA_NAME_IS_DEFAULT_DEF (t))
+ return t;
+
+ gimple *def = SSA_NAME_DEF_STMT (t);
+ if (!is_gimple_assign (def)
+ || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def))
+ || !INTEGRAL_TYPE_P (TREE_TYPE (t))
+ || !INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (def))))
+ return t;
+
+ tree rhs1 = gimple_assign_rhs1 (def);
+ if (TYPE_PRECISION (TREE_TYPE (t))
+ >= TYPE_PRECISION (TREE_TYPE (rhs1)))
+ return gimple_assign_rhs1 (def);
+
+ value_range vr (TREE_TYPE (rhs1));
+ if (!get_range_query (cfun)->range_of_expr (vr, rhs1, def)
+ || vr.undefined_p ())
+ return t;
+
+ irange &ir = as_a <irange> (vr);
+ if (range_fits_type_p (&ir, TYPE_PRECISION (TREE_TYPE (t)),
+ TYPE_SIGN (TREE_TYPE (t))))
+ return gimple_assign_rhs1 (def);
+
+ return t;
+}
+
/* Compute jump function for all arguments of callsite CS and insert the
information in the jump_functions array in the ipa_edge_args corresponding
to this callsite. */
@@ -2415,6 +2454,7 @@ ipa_compute_jump_functions_for_edge (struct ipa_func_body_info *fbi,
gcc_assert (!jfunc->m_vr);
}
+ arg = skip_a_safe_conversion_op (arg);
if (is_gimple_ip_invariant (arg)
|| (VAR_P (arg)
&& is_global_var (arg)
diff --git a/gcc/testsuite/gcc.dg/ipa/vrp9.c b/gcc/testsuite/gcc.dg/ipa/vrp9.c
new file mode 100644
index 000000000000..461a2e757d2c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/vrp9.c
@@ -0,0 +1,48 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+int some_f1 (int);
+int some_f2 (int);
+int some_f3 (int);
+
+void remove_this_call ();
+
+int g;
+
+static int __attribute__((noinline))
+bar (int p)
+{
+ if (p)
+ remove_this_call ();
+ return g++;
+}
+
+static int __attribute__((noinline))
+foo (int (*f)(int))
+{
+ return bar (f == (void *)0);
+}
+
+int
+baz1 (void)
+{
+ int (*f)(int);
+ if (g)
+ f = some_f1;
+ else
+ f = some_f2;
+ return foo (f);
+}
+
+int
+baz2 (void)
+{
+ int (*f)(int);
+ if (g)
+ f = some_f2;
+ else
+ f = some_f3;
+ return foo (f);
+}
+
+/* { dg-final { scan-tree-dump-not "remove_this_call" "optimized" } } */
--
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