[Sema] Support lax conversions for compound assignments

Support lax convertions on compound assignment expressions like:

  typedef __attribute__((vector_size(8))) double float64x1_t;
  typedef __attribute__((vector_size(16))) double float64x2_t;
  float64x1_t vget_low_f64(float64x2_t __p0);

  double c = 3.0;
  float64x2_t v = {0.0, 1.0};
  c += vget_low_f64(v);

This restores one more valid behavior pre r266366, and is a incremental
follow up from work committed in r274646.

While here, make the check more strict, add FIXMEs, clean up variable
names to match what they can actually be and update testcases to reflect
that. We now reject:

  typedef float float2 __attribute__ ((vector_size (8)));
  double d;
  f2 += d;

which doesn't fit as a direct bitcast anyway.

Differential Revision: https://reviews.llvm.org/D24472

rdar://problem/28033929

llvm-svn: 282968

1 files changed, 4 insertions, 5 deletions

diff --git a/clang/test/Sema/vector-cast.c b/clang/test/Sema/vector-cast.c
index c0382892b69..ea4acfac6a0 100644
--- a/clang/test/Sema/vector-cast.c
+++ b/clang/test/Sema/vector-cast.c
@@ -53,14 +53,13 @@ void f4() {
   float2 f2;
   double d, a, b, c;
   float64x2_t v = {0.0, 1.0};
-  f2 += d;
+  // FIXME: These diagnostics are inaccurate: should complain that 'double' to vector 'float2' involves truncation
+  f2 += d; // expected-error {{cannot convert between vector values of different size ('float2' (vector of 2 'float' values) and 'double')}}
+  d += f2; // expected-error {{cannot convert between vector values of different size}}
   a = 3.0 + vget_low_f64(v);
   b = vget_low_f64(v) + 3.0;
   c = vget_low_f64(v);
-  // LAX conversions within compound assignments are not supported.
-  // FIXME: This diagnostic is inaccurate.
-  d += f2; // expected-error {{cannot convert between vector values of different size}}
-  c -= vget_low_f64(v); // expected-error {{cannot convert between vector values of different size}}
+  c -= vget_low_f64(v);
   // LAX conversions between scalar and vector types require same size and one element sized vectors.
   d = f2; // expected-error {{assigning to 'double' from incompatible type 'float2'}}
   d = d + f2; // expected-error {{assigning to 'double' from incompatible type 'float2'}}