[gcc r12-8248] c++: __builtin_shufflevector with value-dep expr [PR105353]

[gcc r12-8248] c++: __builtin_shufflevector with value-dep expr [PR105353]

[Marek Polacek]

https://gcc.gnu.org/g:1ba397e9f93d3abc93a6ecbabc3d873489a6fb7f

commit r12-8248-g1ba397e9f93d3abc93a6ecbabc3d873489a6fb7f
Author: Marek Polacek <polacek@redhat.com>
Date:   Fri Apr 22 19:40:27 2022 -0400

    c++: __builtin_shufflevector with value-dep expr [PR105353]
    
    Here we issue an error from c_build_shufflevector while parsing a template
    because it got a TEMPLATE_PARM_INDEX, but this function expects INTEGER_CSTs
    (except the first two arguments).  It checks if any of the arguments are
    type-dependent, if so, we leave the processing for later, but it should
    also check value-dependency for the 3rd+ arguments, so as to avoid the
    problem above.
    
    This is not a regression -- __builtin_shufflevector was introduced in
    GCC 12, but it looks safe enough.
    
            PR c++/105353
    
    gcc/cp/ChangeLog:
    
            * typeck.cc (build_x_shufflevector): Use
            instantiation_dependent_expression_p except for the first two
            arguments.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/ext/builtin-shufflevector-3.C: New test.

Diff:
---
 gcc/cp/typeck.cc                                   |  4 +++-
 gcc/testsuite/g++.dg/ext/builtin-shufflevector-3.C | 23 ++++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc
index 26a7cb4b50d..0da6f2485d0 100644
--- a/gcc/cp/typeck.cc
+++ b/gcc/cp/typeck.cc
@@ -6315,7 +6315,9 @@ build_x_shufflevector (location_t loc, vec<tree, va_gc> *args,
   if (processing_template_decl)
     {
       for (unsigned i = 0; i < args->length (); ++i)
-	if (type_dependent_expression_p ((*args)[i]))
+	if (i <= 1
+	    ? type_dependent_expression_p ((*args)[i])
+	    : instantiation_dependent_expression_p ((*args)[i]))
 	  {
 	    tree exp = build_min_nt_call_vec (NULL, args);
 	    CALL_EXPR_IFN (exp) = IFN_SHUFFLEVECTOR;
diff --git a/gcc/testsuite/g++.dg/ext/builtin-shufflevector-3.C b/gcc/testsuite/g++.dg/ext/builtin-shufflevector-3.C
new file mode 100644
index 00000000000..0f3cbbee563
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/builtin-shufflevector-3.C
@@ -0,0 +1,23 @@
+// PR c++/105353
+// { dg-do compile { target c++17 } }
+// { dg-additional-options "-Wno-psabi" }
+
+typedef unsigned char Simd128U8VectT __attribute__((__vector_size__(16)));
+
+template<int ShuffleIndex>
+static inline Simd128U8VectT ShufFunc(Simd128U8VectT vect) noexcept {
+    if constexpr(unsigned(ShuffleIndex) >= 16)
+        return Simd128U8VectT { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+    else if constexpr(ShuffleIndex == 0)
+        return vect;
+    else
+        return __builtin_shufflevector(vect, vect, ShuffleIndex, ShuffleIndex + 1,
+            ShuffleIndex + 2, ShuffleIndex + 3, ShuffleIndex + 4, ShuffleIndex + 5,
+            ShuffleIndex + 6, ShuffleIndex + 7, ShuffleIndex + 8, ShuffleIndex + 9,
+            ShuffleIndex + 10, ShuffleIndex + 11, ShuffleIndex + 12, ShuffleIndex + 13,
+            ShuffleIndex + 14, ShuffleIndex + 15);
+}
+
+auto func1(Simd128U8VectT vect) noexcept {
+    return ShufFunc<5>(vect);
+}