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| <a name="Vectors"></a> |
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| Previous: <a href="Unary-and-Binary-Expressions.html#Unary-and-Binary-Expressions" accesskey="p" rel="prev">Unary and Binary Expressions</a>, Up: <a href="Expression-trees.html#Expression-trees" accesskey="u" rel="up">Expression trees</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> |
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| <a name="Vectors-1"></a> |
| <h4 class="subsection">10.6.4 Vectors</h4> |
| <a name="index-VEC_005fLSHIFT_005fEXPR"></a> |
| <a name="index-VEC_005fRSHIFT_005fEXPR"></a> |
| <a name="index-VEC_005fWIDEN_005fMULT_005fHI_005fEXPR"></a> |
| <a name="index-VEC_005fWIDEN_005fMULT_005fLO_005fEXPR"></a> |
| <a name="index-VEC_005fUNPACK_005fHI_005fEXPR"></a> |
| <a name="index-VEC_005fUNPACK_005fLO_005fEXPR"></a> |
| <a name="index-VEC_005fUNPACK_005fFLOAT_005fHI_005fEXPR"></a> |
| <a name="index-VEC_005fUNPACK_005fFLOAT_005fLO_005fEXPR"></a> |
| <a name="index-VEC_005fPACK_005fTRUNC_005fEXPR"></a> |
| <a name="index-VEC_005fPACK_005fSAT_005fEXPR"></a> |
| <a name="index-VEC_005fPACK_005fFIX_005fTRUNC_005fEXPR"></a> |
| |
| <dl compact="compact"> |
| <dt><code>VEC_LSHIFT_EXPR</code></dt> |
| <dt><code>VEC_RSHIFT_EXPR</code></dt> |
| <dd><p>These nodes represent whole vector left and right shifts, respectively. |
| The first operand is the vector to shift; it will always be of vector type. |
| The second operand is an expression for the number of bits by which to |
| shift. Note that the result is undefined if the second operand is larger |
| than or equal to the first operand’s type size. |
| </p> |
| </dd> |
| <dt><code>VEC_WIDEN_MULT_HI_EXPR</code></dt> |
| <dt><code>VEC_WIDEN_MULT_LO_EXPR</code></dt> |
| <dd><p>These nodes represent widening vector multiplication of the high and low |
| parts of the two input vectors, respectively. Their operands are vectors |
| that contain the same number of elements (<code>N</code>) of the same integral type. |
| The result is a vector that contains half as many elements, of an integral type |
| whose size is twice as wide. In the case of <code>VEC_WIDEN_MULT_HI_EXPR</code> the |
| high <code>N/2</code> elements of the two vector are multiplied to produce the |
| vector of <code>N/2</code> products. In the case of <code>VEC_WIDEN_MULT_LO_EXPR</code> the |
| low <code>N/2</code> elements of the two vector are multiplied to produce the |
| vector of <code>N/2</code> products. |
| </p> |
| </dd> |
| <dt><code>VEC_UNPACK_HI_EXPR</code></dt> |
| <dt><code>VEC_UNPACK_LO_EXPR</code></dt> |
| <dd><p>These nodes represent unpacking of the high and low parts of the input vector, |
| respectively. The single operand is a vector that contains <code>N</code> elements |
| of the same integral or floating point type. The result is a vector |
| that contains half as many elements, of an integral or floating point type |
| whose size is twice as wide. In the case of <code>VEC_UNPACK_HI_EXPR</code> the |
| high <code>N/2</code> elements of the vector are extracted and widened (promoted). |
| In the case of <code>VEC_UNPACK_LO_EXPR</code> the low <code>N/2</code> elements of the |
| vector are extracted and widened (promoted). |
| </p> |
| </dd> |
| <dt><code>VEC_UNPACK_FLOAT_HI_EXPR</code></dt> |
| <dt><code>VEC_UNPACK_FLOAT_LO_EXPR</code></dt> |
| <dd><p>These nodes represent unpacking of the high and low parts of the input vector, |
| where the values are converted from fixed point to floating point. The |
| single operand is a vector that contains <code>N</code> elements of the same |
| integral type. The result is a vector that contains half as many elements |
| of a floating point type whose size is twice as wide. In the case of |
| <code>VEC_UNPACK_HI_EXPR</code> the high <code>N/2</code> elements of the vector are |
| extracted, converted and widened. In the case of <code>VEC_UNPACK_LO_EXPR</code> |
| the low <code>N/2</code> elements of the vector are extracted, converted and widened. |
| </p> |
| </dd> |
| <dt><code>VEC_PACK_TRUNC_EXPR</code></dt> |
| <dd><p>This node represents packing of truncated elements of the two input vectors |
| into the output vector. Input operands are vectors that contain the same |
| number of elements of the same integral or floating point type. The result |
| is a vector that contains twice as many elements of an integral or floating |
| point type whose size is half as wide. The elements of the two vectors are |
| demoted and merged (concatenated) to form the output vector. |
| </p> |
| </dd> |
| <dt><code>VEC_PACK_SAT_EXPR</code></dt> |
| <dd><p>This node represents packing of elements of the two input vectors into the |
| output vector using saturation. Input operands are vectors that contain |
| the same number of elements of the same integral type. The result is a |
| vector that contains twice as many elements of an integral type whose size |
| is half as wide. The elements of the two vectors are demoted and merged |
| (concatenated) to form the output vector. |
| </p> |
| </dd> |
| <dt><code>VEC_PACK_FIX_TRUNC_EXPR</code></dt> |
| <dd><p>This node represents packing of elements of the two input vectors into the |
| output vector, where the values are converted from floating point |
| to fixed point. Input operands are vectors that contain the same number |
| of elements of a floating point type. The result is a vector that contains |
| twice as many elements of an integral type whose size is half as wide. The |
| elements of the two vectors are merged (concatenated) to form the output |
| vector. |
| </p> |
| </dd> |
| <dt><code>VEC_COND_EXPR</code></dt> |
| <dd><p>These nodes represent <code>?:</code> expressions. The three operands must be |
| vectors of the same size and number of elements. The second and third |
| operands must have the same type as the entire expression. The first |
| operand is of signed integral vector type. If an element of the first |
| operand evaluates to a zero value, the corresponding element of the |
| result is taken from the third operand. If it evaluates to a minus one |
| value, it is taken from the second operand. It should never evaluate to |
| any other value currently, but optimizations should not rely on that |
| property. In contrast with a <code>COND_EXPR</code>, all operands are always |
| evaluated. |
| </p></dd> |
| </dl> |
| |
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