[clang] 1d78294 - [Sema][BFloat] Forbid arithmetic on vectors of bfloat.

[Simon Tatham via cfe-commits]

Author: Simon Tatham
Date: 2020-08-07T11:25:19+01:00
New Revision: 1d782942500b2cbc9765ccf16264bb498850cefb

URL: https://github.com/llvm/llvm-project/commit/1d782942500b2cbc9765ccf16264bb498850cefb
DIFF: https://github.com/llvm/llvm-project/commit/1d782942500b2cbc9765ccf16264bb498850cefb.diff

LOG: [Sema][BFloat] Forbid arithmetic on vectors of bfloat.

Vectors of bfloat are a storage format only; you're supposed to
explicitly convert them to a wider type to do arithmetic on them.
But currently, if you write something like

  bfloat16x4_t test(bfloat16x4_t a, bfloat16x4_t b) { return a + b; }

then the clang frontend accepts it without error, and (ARM or AArch64)
isel fails to generate code for it.

Added a rule in Sema that forbids the attempt from even being made,
and tests that check it. In particular, we also outlaw arithmetic
between vectors of bfloat and any other vector type.

Patch by Luke Cheeseman.

Reviewed By: LukeGeeson

Differential Revision: https://reviews.llvm.org/D85009

Added: 
    

Modified: 
    clang/lib/Sema/SemaExpr.cpp
    clang/test/Sema/arm-bfloat.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 4931cf46cffd..b681c930b2a7 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -9789,6 +9789,10 @@ QualType Sema::CheckVectorOperands(ExprResult &LHS, ExprResult &RHS,
   const VectorType *RHSVecType = RHSType->getAs<VectorType>();
   assert(LHSVecType || RHSVecType);
 
+  if ((LHSVecType && LHSVecType->getElementType()->isBFloat16Type()) ||
+      (RHSVecType && RHSVecType->getElementType()->isBFloat16Type()))
+    return InvalidOperands(Loc, LHS, RHS);
+
   // AltiVec-style "vector bool op vector bool" combinations are allowed
   // for some operators but not others.
   if (!AllowBothBool &&

diff  --git a/clang/test/Sema/arm-bfloat.cpp b/clang/test/Sema/arm-bfloat.cpp
index f7ee3c596eb8..ce3fc44baa39 100644
--- a/clang/test/Sema/arm-bfloat.cpp
+++ b/clang/test/Sema/arm-bfloat.cpp
@@ -27,3 +27,21 @@ void test(bool b) {
   fp16 = bf16; // expected-error {{assigning to '__fp16' from incompatible type '__bf16'}}
   bf16 + (b ? fp16 : bf16); // expected-error {{incompatible operand types ('__fp16' and '__bf16')}}
 }
+
+#include <arm_neon.h>
+
+void test_vector(bfloat16x4_t a, bfloat16x4_t b, float16x4_t c) {
+  a + b; // expected-error {{invalid operands to binary expression ('bfloat16x4_t' (vector of 4 'bfloat16_t' values) and 'bfloat16x4_t')}}
+  a - b; // expected-error {{invalid operands to binary expression ('bfloat16x4_t' (vector of 4 'bfloat16_t' values) and 'bfloat16x4_t')}}
+  a * b; // expected-error {{invalid operands to binary expression ('bfloat16x4_t' (vector of 4 'bfloat16_t' values) and 'bfloat16x4_t')}}
+  a / b; // expected-error {{invalid operands to binary expression ('bfloat16x4_t' (vector of 4 'bfloat16_t' values) and 'bfloat16x4_t')}}
+
+  a + c; // expected-error {{invalid operands to binary expression ('bfloat16x4_t' (vector of 4 'bfloat16_t' values) and 'float16x4_t' (vector of 4 'float16_t' values))}}
+  a - c; // expected-error {{invalid operands to binary expression ('bfloat16x4_t' (vector of 4 'bfloat16_t' values) and 'float16x4_t' (vector of 4 'float16_t' values))}}
+  a * c; // expected-error {{invalid operands to binary expression ('bfloat16x4_t' (vector of 4 'bfloat16_t' values) and 'float16x4_t' (vector of 4 'float16_t' values))}}
+  a / c; // expected-error {{invalid operands to binary expression ('bfloat16x4_t' (vector of 4 'bfloat16_t' values) and 'float16x4_t' (vector of 4 'float16_t' values))}}
+  c + b; // expected-error {{invalid operands to binary expression ('float16x4_t' (vector of 4 'float16_t' values) and 'bfloat16x4_t' (vector of 4 'bfloat16_t' values))}}
+  c - b; // expected-error {{invalid operands to binary expression ('float16x4_t' (vector of 4 'float16_t' values) and 'bfloat16x4_t' (vector of 4 'bfloat16_t' values))}}
+  c * b; // expected-error {{invalid operands to binary expression ('float16x4_t' (vector of 4 'float16_t' values) and 'bfloat16x4_t' (vector of 4 'bfloat16_t' values))}}
+  c / b; // expected-error {{invalid operands to binary expression ('float16x4_t' (vector of 4 'float16_t' values) and 'bfloat16x4_t' (vector of 4 'bfloat16_t' values))}}
+}