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Enable support for vector sext and trunc:

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Limit the folding of any_ext and sext  into the load operation to scalars.
Limit the active-bits trunc optimization to scalars.
Document vector trunc and vector sext in LangRef.

Similar to commit 126080 (for enabling zext).



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126424 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem 2011-02-24 21:01:34 +00:00
parent 0412d5b40a
commit 8c20ec54d9
4 changed files with 179 additions and 23 deletions
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29
docs/LangRef.html
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@ -4575,12 +4575,12 @@ entry:
type <tt>ty2</tt>.</p>
<h5>Arguments:</h5>
<p>The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must
be an <a href="#t_integer">integer</a> type, and a type that specifies the
size and type of the result, which must be
an <a href="#t_integer">integer</a> type. The bit size of <tt>value</tt> must
be larger than the bit size of <tt>ty2</tt>. Equal sized types are not
allowed.</p>
<p>The '<tt>trunc</tt>' instruction takes a value to trunc, and a type to trunc it to.
Both types must be of <a href="#t_integer">integer</a> types, or vectors
of the same number of integers.
The bit size of the <tt>value</tt> must be larger than
the bit size of the destination type, <tt>ty2</tt>.
Equal sized types are not allowed.</p>
<h5>Semantics:</h5>
<p>The '<tt>trunc</tt>' instruction truncates the high order bits
@ -4590,9 +4590,10 @@ entry:
<h5>Example:</h5>
<pre>
%X = trunc i32 257 to i8 <i>; yields i8:1</i>
%Y = trunc i32 123 to i1 <i>; yields i1:true</i>
%Z = trunc i32 122 to i1 <i>; yields i1:false</i>
%X = trunc i32 257 to i8 <i>; yields i8:1</i>
%Y = trunc i32 123 to i1 <i>; yields i1:true</i>
%Z = trunc i32 122 to i1 <i>; yields i1:false</i>
%W = trunc &lt;2 x i16&gt; &lt;i16 8, i16 7&gt; to &lt;2 x i8&gt; <i>; yields &lt;i8 8, i8 7&gt;</i>
</pre>
</div>
@ -4651,10 +4652,11 @@ entry:
<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>
<h5>Arguments:</h5>
<p>The '<tt>sext</tt>' instruction takes a value to cast, which must be of
<a href="#t_integer">integer</a> type, and a type to cast it to, which must
also be of <a href="#t_integer">integer</a> type. The bit size of the
<tt>value</tt> must be smaller than the bit size of the destination type,
<p>The '<tt>sext</tt>' instruction takes a value to cast, and a type to cast it to.
Both types must be of <a href="#t_integer">integer</a> types, or vectors
of the same number of integers.
The bit size of the <tt>value</tt> must be smaller than
the bit size of the destination type,
<tt>ty2</tt>.</p>
<h5>Semantics:</h5>
@ -4668,6 +4670,7 @@ entry:
<pre>
%X = sext i8 -1 to i16 <i>; yields i16 :65535</i>
%Y = sext i1 true to i32 <i>; yields i32:-1</i>
%Z = sext &lt;2 x i16&gt; &lt;i16 8, i16 7&gt; to &lt;2 x i32&gt; <i>; yields &lt;i32 8, i32 7&gt;</i>
</pre>
</div>

27
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -3685,7 +3685,9 @@ SDValue DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
}
// fold (sext (load x)) -> (sext (truncate (sextload x)))
if (ISD::isNON_EXTLoad(N0.getNode()) &&
// None of the supported targets knows how to perform load and sign extend
// in one instruction. We only perform this transformation on scalars.
if (ISD::isNON_EXTLoad(N0.getNode()) && !VT.isVector() &&
((!LegalOperations && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadExtLegal(ISD::SEXTLOAD, N0.getValueType()))) {
bool DoXform = true;
@ -4096,7 +4098,9 @@ SDValue DAGCombiner::visitANY_EXTEND(SDNode *N) {
}
// fold (aext (load x)) -> (aext (truncate (extload x)))
if (ISD::isNON_EXTLoad(N0.getNode()) &&
// None of the supported targets knows how to perform load and any_ext
// in one instruction. We only perform this transformation on scalars.
if (ISD::isNON_EXTLoad(N0.getNode()) && !VT.isVector() &&
((!LegalOperations && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadExtLegal(ISD::EXTLOAD, N0.getValueType()))) {
bool DoXform = true;
@ -4506,14 +4510,17 @@ SDValue DAGCombiner::visitTRUNCATE(SDNode *N) {
}
// See if we can simplify the input to this truncate through knowledge that
// only the low bits are being used. For example "trunc (or (shl x, 8), y)"
// -> trunc y
SDValue Shorter =
GetDemandedBits(N0, APInt::getLowBitsSet(N0.getValueSizeInBits(),
VT.getSizeInBits()));
if (Shorter.getNode())
return DAG.getNode(ISD::TRUNCATE, N->getDebugLoc(), VT, Shorter);
// only the low bits are being used.
// For example "trunc (or (shl x, 8), y)" // -> trunc y
// Currenly we only perform this optimization on scalars because vectors
// may have different active low bits.
if (!VT.isVector()) {
SDValue Shorter =
GetDemandedBits(N0, APInt::getLowBitsSet(N0.getValueSizeInBits(),
VT.getSizeInBits()));
if (Shorter.getNode())
return DAG.getNode(ISD::TRUNCATE, N->getDebugLoc(), VT, Shorter);
}
// fold (truncate (load x)) -> (smaller load x)
// fold (truncate (srl (load x), c)) -> (smaller load (x+c/evtbits))
if (!LegalTypes || TLI.isTypeDesirableForOp(N0.getOpcode(), VT)) {

77
test/CodeGen/X86/vec_anyext.ll Normal file
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@ -0,0 +1,77 @@
; RUN: llc < %s -march=x86-64
; PR 9267
define<4 x i16> @func_16_32() {
%F = load <4 x i32>* undef
%G = trunc <4 x i32> %F to <4 x i16>
%H = load <4 x i32>* undef
%Y = trunc <4 x i32> %H to <4 x i16>
%T = add <4 x i16> %Y, %G
store <4 x i16>%T , <4 x i16>* undef
ret <4 x i16> %T
}
define<4 x i16> @func_16_64() {
%F = load <4 x i64>* undef
%G = trunc <4 x i64> %F to <4 x i16>
%H = load <4 x i64>* undef
%Y = trunc <4 x i64> %H to <4 x i16>
%T = xor <4 x i16> %Y, %G
store <4 x i16>%T , <4 x i16>* undef
ret <4 x i16> %T
}
define<4 x i32> @func_32_64() {
%F = load <4 x i64>* undef
%G = trunc <4 x i64> %F to <4 x i32>
%H = load <4 x i64>* undef
%Y = trunc <4 x i64> %H to <4 x i32>
%T = or <4 x i32> %Y, %G
ret <4 x i32> %T
}
define<4 x i8> @func_8_16() {
%F = load <4 x i16>* undef
%G = trunc <4 x i16> %F to <4 x i8>
%H = load <4 x i16>* undef
%Y = trunc <4 x i16> %H to <4 x i8>
%T = add <4 x i8> %Y, %G
ret <4 x i8> %T
}
define<4 x i8> @func_8_32() {
%F = load <4 x i32>* undef
%G = trunc <4 x i32> %F to <4 x i8>
%H = load <4 x i32>* undef
%Y = trunc <4 x i32> %H to <4 x i8>
%T = sub <4 x i8> %Y, %G
ret <4 x i8> %T
}
define<4 x i8> @func_8_64() {
%F = load <4 x i64>* undef
%G = trunc <4 x i64> %F to <4 x i8>
%H = load <4 x i64>* undef
%Y = trunc <4 x i64> %H to <4 x i8>
%T = add <4 x i8> %Y, %G
ret <4 x i8> %T
}
define<4 x i16> @const_16_32() {
%G = trunc <4 x i32> <i32 0, i32 3, i32 8, i32 7> to <4 x i16>
ret <4 x i16> %G
}
define<4 x i16> @const_16_64() {
%G = trunc <4 x i64> <i64 0, i64 3, i64 8, i64 7> to <4 x i16>
ret <4 x i16> %G
}
define void @bugOnTruncBitwidthReduce() nounwind {
meh:
%0 = xor <4 x i64> zeroinitializer, zeroinitializer
%1 = trunc <4 x i64> %0 to <4 x i32>
%2 = lshr <4 x i32> %1, <i32 18, i32 18, i32 18, i32 18>
%3 = xor <4 x i32> %2, %1
ret void
}

69
test/CodeGen/X86/vec_sext.ll Normal file
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@ -0,0 +1,69 @@
; RUN: llc < %s -march=x86-64
; PR 9267
define<4 x i32> @func_16_32() {
%F = load <4 x i16>* undef
%G = sext <4 x i16> %F to <4 x i32>
%H = load <4 x i16>* undef
%Y = sext <4 x i16> %H to <4 x i32>
%T = add <4 x i32> %Y, %G
store <4 x i32>%T , <4 x i32>* undef
ret <4 x i32> %T
}
define<4 x i64> @func_16_64() {
%F = load <4 x i16>* undef
%G = sext <4 x i16> %F to <4 x i64>
%H = load <4 x i16>* undef
%Y = sext <4 x i16> %H to <4 x i64>
%T = xor <4 x i64> %Y, %G
store <4 x i64>%T , <4 x i64>* undef
ret <4 x i64> %T
}
define<4 x i64> @func_32_64() {
%F = load <4 x i32>* undef
%G = sext <4 x i32> %F to <4 x i64>
%H = load <4 x i32>* undef
%Y = sext <4 x i32> %H to <4 x i64>
%T = or <4 x i64> %Y, %G
ret <4 x i64> %T
}
define<4 x i16> @func_8_16() {
%F = load <4 x i8>* undef
%G = sext <4 x i8> %F to <4 x i16>
%H = load <4 x i8>* undef
%Y = sext <4 x i8> %H to <4 x i16>
%T = add <4 x i16> %Y, %G
ret <4 x i16> %T
}
define<4 x i32> @func_8_32() {
%F = load <4 x i8>* undef
%G = sext <4 x i8> %F to <4 x i32>
%H = load <4 x i8>* undef
%Y = sext <4 x i8> %H to <4 x i32>
%T = sub <4 x i32> %Y, %G
ret <4 x i32> %T
}
define<4 x i64> @func_8_64() {
%F = load <4 x i8>* undef
%G = sext <4 x i8> %F to <4 x i64>
%H = load <4 x i8>* undef
%Y = sext <4 x i8> %H to <4 x i64>
%T = add <4 x i64> %Y, %G
ret <4 x i64> %T
}
define<4 x i32> @const_16_32() {
%G = sext <4 x i16> <i16 0, i16 3, i16 8, i16 7> to <4 x i32>
ret <4 x i32> %G
}
define<4 x i64> @const_16_64() {
%G = sext <4 x i16> <i16 0, i16 3, i16 8, i16 7> to <4 x i64>
ret <4 x i64> %G
}