From 84993d94e13ad2ab3aee151bb5a5e767cf75d51e Mon Sep 17 00:00:00 2001
From: Jakub Jelinek <jakub@redhat.com>
Date: Fri, 11 Feb 2022 13:52:44 +0100
Subject: [PATCH] c++: Fix up constant expression __builtin_convertvector
folding [PR104472]
The following testcase ICEs, because due to the -frounding-math
fold_const_call fails, which is it returns NULL, and returning NULL from
cxx_eval* is wrong, all the callers rely on them to either return folded
value or original with *non_constant_p = true.
The following patch does that, and additionally falls through into the
default case where there is diagnostics for the !ctx->quiet case too.
2022-02-11 Jakub Jelinek <jakub@redhat.com>
PR c++/104472
* constexpr.cc (cxx_eval_internal_function) <case IFN_VEC_CONVERT>:
Only return fold_const_call result if it is non-NULL. Otherwise
fall through into the default: case to return t, set *non_constant_p
and emit diagnostics if needed.
* g++.dg/cpp0x/constexpr-104472.C: New test.
---
gcc/cp/constexpr.cc | 9 +++------
gcc/testsuite/g++.dg/cpp0x/constexpr-104472.C | 9 +++++++++
2 files changed, 12 insertions(+), 6 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp0x/constexpr-104472.C
diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index 9b8e0eced4b8..87f3a7bb7a33 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -1840,13 +1840,10 @@ cxx_eval_internal_function (const constexpr_ctx *ctx, tree t,
false, non_constant_p,
overflow_p);
if (TREE_CODE (arg) == VECTOR_CST)
- return fold_const_call (CFN_VEC_CONVERT, TREE_TYPE (t), arg);
- else
- {
- *non_constant_p = true;
- return t;
- }
+ if (tree r = fold_const_call (CFN_VEC_CONVERT, TREE_TYPE (t), arg))
+ return r;
}
+ /* FALLTHRU */
default:
if (!ctx->quiet)
diff --git a/gcc/testsuite/g++.dg/cpp0x/constexpr-104472.C b/gcc/testsuite/g++.dg/cpp0x/constexpr-104472.C
new file mode 100644
index 000000000000..c9c8bf414fee
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/constexpr-104472.C
@@ -0,0 +1,9 @@
+// PR c++/104472
+// { dg-options "-O2 -frounding-math" }
+// { dg-add-options float16 }
+// { dg-require-effective-target float16 }
+
+typedef short __attribute__((__vector_size__ (16))) V;
+typedef _Float16 __attribute__((__vector_size__ (16))) F;
+
+V v = __builtin_convertvector (__builtin_convertvector ((V){5534}, F), V) < 8;
--
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