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138 lines
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138 lines
8.1 KiB
HTML
4 years ago
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<title>Vectors - GNU Compiler Collection (GCC) Internals</title>
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<link rel="up" href="Expression-trees.html#Expression-trees" title="Expression trees">
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<link rel="prev" href="Unary-and-Binary-Expressions.html#Unary-and-Binary-Expressions" title="Unary and Binary Expressions">
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Copyright (C) 1988-2015 Free Software Foundation, Inc.
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Permission is granted to copy, distribute and/or modify this document
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(a) The FSF's Front-Cover Text is:
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A GNU Manual
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</head>
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<body>
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<div class="node">
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<a name="Vectors"></a>
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<p>
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Previous: <a rel="previous" accesskey="p" href="Unary-and-Binary-Expressions.html#Unary-and-Binary-Expressions">Unary and Binary Expressions</a>,
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Up: <a rel="up" accesskey="u" href="Expression-trees.html#Expression-trees">Expression trees</a>
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<hr>
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</div>
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<h4 class="subsection">10.6.4 Vectors</h4>
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<p><a name="index-VEC_005fLSHIFT_005fEXPR-1924"></a><a name="index-VEC_005fRSHIFT_005fEXPR-1925"></a><a name="index-VEC_005fWIDEN_005fMULT_005fHI_005fEXPR-1926"></a><a name="index-VEC_005fWIDEN_005fMULT_005fLO_005fEXPR-1927"></a><a name="index-VEC_005fUNPACK_005fHI_005fEXPR-1928"></a><a name="index-VEC_005fUNPACK_005fLO_005fEXPR-1929"></a><a name="index-VEC_005fUNPACK_005fFLOAT_005fHI_005fEXPR-1930"></a><a name="index-VEC_005fUNPACK_005fFLOAT_005fLO_005fEXPR-1931"></a><a name="index-VEC_005fPACK_005fTRUNC_005fEXPR-1932"></a><a name="index-VEC_005fPACK_005fSAT_005fEXPR-1933"></a><a name="index-VEC_005fPACK_005fFIX_005fTRUNC_005fEXPR-1934"></a><a name="index-SAD_005fEXPR-1935"></a>
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<dl>
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<dt><code>VEC_LSHIFT_EXPR</code><dt><code>VEC_RSHIFT_EXPR</code><dd>These nodes represent whole vector left and right shifts, respectively.
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The first operand is the vector to shift; it will always be of vector type.
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The second operand is an expression for the number of bits by which to
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shift. Note that the result is undefined if the second operand is larger
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than or equal to the first operand's type size.
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<br><dt><code>VEC_WIDEN_MULT_HI_EXPR</code><dt><code>VEC_WIDEN_MULT_LO_EXPR</code><dd>These nodes represent widening vector multiplication of the high and low
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parts of the two input vectors, respectively. Their operands are vectors
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that contain the same number of elements (<code>N</code>) of the same integral type.
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The result is a vector that contains half as many elements, of an integral type
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whose size is twice as wide. In the case of <code>VEC_WIDEN_MULT_HI_EXPR</code> the
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high <code>N/2</code> elements of the two vector are multiplied to produce the
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vector of <code>N/2</code> products. In the case of <code>VEC_WIDEN_MULT_LO_EXPR</code> the
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low <code>N/2</code> elements of the two vector are multiplied to produce the
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vector of <code>N/2</code> products.
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<br><dt><code>VEC_UNPACK_HI_EXPR</code><dt><code>VEC_UNPACK_LO_EXPR</code><dd>These nodes represent unpacking of the high and low parts of the input vector,
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respectively. The single operand is a vector that contains <code>N</code> elements
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of the same integral or floating point type. The result is a vector
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that contains half as many elements, of an integral or floating point type
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whose size is twice as wide. In the case of <code>VEC_UNPACK_HI_EXPR</code> the
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high <code>N/2</code> elements of the vector are extracted and widened (promoted).
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In the case of <code>VEC_UNPACK_LO_EXPR</code> the low <code>N/2</code> elements of the
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vector are extracted and widened (promoted).
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<br><dt><code>VEC_UNPACK_FLOAT_HI_EXPR</code><dt><code>VEC_UNPACK_FLOAT_LO_EXPR</code><dd>These nodes represent unpacking of the high and low parts of the input vector,
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where the values are converted from fixed point to floating point. The
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single operand is a vector that contains <code>N</code> elements of the same
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integral type. The result is a vector that contains half as many elements
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of a floating point type whose size is twice as wide. In the case of
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<code>VEC_UNPACK_HI_EXPR</code> the high <code>N/2</code> elements of the vector are
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extracted, converted and widened. In the case of <code>VEC_UNPACK_LO_EXPR</code>
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the low <code>N/2</code> elements of the vector are extracted, converted and widened.
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<br><dt><code>VEC_PACK_TRUNC_EXPR</code><dd>This node represents packing of truncated elements of the two input vectors
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into the output vector. Input operands are vectors that contain the same
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number of elements of the same integral or floating point type. The result
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is a vector that contains twice as many elements of an integral or floating
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point type whose size is half as wide. The elements of the two vectors are
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demoted and merged (concatenated) to form the output vector.
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<br><dt><code>VEC_PACK_SAT_EXPR</code><dd>This node represents packing of elements of the two input vectors into the
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output vector using saturation. Input operands are vectors that contain
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the same number of elements of the same integral type. The result is a
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vector that contains twice as many elements of an integral type whose size
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is half as wide. The elements of the two vectors are demoted and merged
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(concatenated) to form the output vector.
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<br><dt><code>VEC_PACK_FIX_TRUNC_EXPR</code><dd>This node represents packing of elements of the two input vectors into the
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output vector, where the values are converted from floating point
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to fixed point. Input operands are vectors that contain the same number
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of elements of a floating point type. The result is a vector that contains
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twice as many elements of an integral type whose size is half as wide. The
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elements of the two vectors are merged (concatenated) to form the output
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vector.
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<br><dt><code>VEC_COND_EXPR</code><dd>These nodes represent <code>?:</code> expressions. The three operands must be
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vectors of the same size and number of elements. The second and third
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operands must have the same type as the entire expression. The first
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operand is of signed integral vector type. If an element of the first
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operand evaluates to a zero value, the corresponding element of the
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result is taken from the third operand. If it evaluates to a minus one
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value, it is taken from the second operand. It should never evaluate to
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any other value currently, but optimizations should not rely on that
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property. In contrast with a <code>COND_EXPR</code>, all operands are always
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evaluated.
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<br><dt><code>SAD_EXPR</code><dd>This node represents the Sum of Absolute Differences operation. The three
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operands must be vectors of integral types. The first and second operand
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must have the same type. The size of the vector element of the third
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operand must be at lease twice of the size of the vector element of the
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first and second one. The SAD is calculated between the first and second
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operands, added to the third operand, and returned.
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</dl>
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<!-- -->
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