Chris Lattner 867b99f845 add a new SimplifyDemandedVectorElts method, which works similarly to ... SimplifyDemandedBits. The idea is that some operations can be simplified if not all of the computed elements are needed. Some targets (like x86) have a large number of intrinsics that operate on a single element, but pass other elts through unmodified. If those other elements are not needed, the intrinsics can be simplified to scalar operations, and insertelement ops can be removed. This turns (f.e.): ushort %Convert_sse(float %f) { %tmp = insertelement <4 x float> undef, float %f, uint 0 ; <<4 x float>> [#uses=1] %tmp10 = insertelement <4 x float> %tmp, float 0.000000e+00, uint 1 ; <<4 x float>> [#uses=1] %tmp11 = insertelement <4 x float> %tmp10, float 0.000000e+00, uint 2 ; <<4 x float>> [#uses=1] %tmp12 = insertelement <4 x float> %tmp11, float 0.000000e+00, uint 3 ; <<4 x float>> [#uses=1] %tmp28 = tail call <4 x float> %llvm.x86.sse.sub.ss( <4 x float> %tmp12, <4 x float> < float 1.000000e+00, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00 > ) ; <<4 x float>> [#uses=1] %tmp37 = tail call <4 x float> %llvm.x86.sse.mul.ss( <4 x float> %tmp28, <4 x float> < float 5.000000e-01, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00 > ) ; <<4 x float>> [#uses=1] %tmp48 = tail call <4 x float> %llvm.x86.sse.min.ss( <4 x float> %tmp37, <4 x float> < float 6.553500e+04, float 0.000000e+00, float 0.000000e+00, float 0.000000e+00 > ) ; <<4 x float>> [#uses=1] %tmp59 = tail call <4 x float> %llvm.x86.sse.max.ss( <4 x float> %tmp48, <4 x float> zeroinitializer ) ; <<4 x float>> [#uses=1] %tmp = tail call int %llvm.x86.sse.cvttss2si( <4 x float> %tmp59 ) ; <int> [#uses=1] %tmp69 = cast int %tmp to ushort ; <ushort> [#uses=1] ret ushort %tmp69 } into: ushort %Convert_sse(float %f) { entry: %tmp28 = sub float %f, 1.000000e+00 ; <float> [#uses=1] %tmp37 = mul float %tmp28, 5.000000e-01 ; <float> [#uses=1] %tmp375 = insertelement <4 x float> undef, float %tmp37, uint 0 ; <<4 x float>> [#uses=1] %tmp48 = tail call <4 x float> %llvm.x86.sse.min.ss( <4 x float> %tmp375, <4 x float> < float 6.553500e+04, float undef, float undef, float undef > ) ; <<4 x float>> [#uses=1] %tmp59 = tail call <4 x float> %llvm.x86.sse.max.ss( <4 x float> %tmp48, <4 x float> < float 0.000000e+00, float undef, float undef, float undef > ) ; <<4 x float>> [#uses=1] %tmp = tail call int %llvm.x86.sse.cvttss2si( <4 x float> %tmp59 ) ; <int> [#uses=1] %tmp69 = cast int %tmp to ushort ; <ushort> [#uses=1] ret ushort %tmp69 } which improves codegen from: _Convert_sse: movss LCPI1_0, %xmm0 movss 4(%esp), %xmm1 subss %xmm0, %xmm1 movss LCPI1_1, %xmm0 mulss %xmm0, %xmm1 movss LCPI1_2, %xmm0 minss %xmm0, %xmm1 xorps %xmm0, %xmm0 maxss %xmm0, %xmm1 cvttss2si %xmm1, %eax andl $65535, %eax ret to: _Convert_sse: movss 4(%esp), %xmm0 subss LCPI1_0, %xmm0 mulss LCPI1_1, %xmm0 movss LCPI1_2, %xmm1 minss %xmm1, %xmm0 xorps %xmm1, %xmm1 maxss %xmm1, %xmm0 cvttss2si %xmm0, %eax andl $65535, %eax ret This is just a first step, it can be extended in many ways. Testcase here: Transforms/InstCombine/vec_demanded_elts.ll git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30752 91177308-0d34-0410-b5e6-96231b3b80d8		2006-10-05 06:55:50 +00:00
..
Hello	eliminate RegisterOpt. It does the same thing as RegisterPass.	2006-08-27 22:42:52 +00:00
Instrumentation	simplify AnalysisGroup registration, eliminating one typeid call.	2006-08-28 00:42:29 +00:00
IPO	Revert previous patch. Still breaking things.	2006-10-03 07:26:07 +00:00
Scalar	add a new SimplifyDemandedVectorElts method, which works similarly to	2006-10-05 06:55:50 +00:00
Utils	This case isn't implemented yet. It seems unlikely to be needed, but if it	2006-10-04 04:58:58 +00:00
ExprTypeConvert.cpp	Remove dead stuff	2006-05-12 23:32:01 +00:00
LevelRaise.cpp	eliminate RegisterOpt. It does the same thing as RegisterPass.	2006-08-27 22:42:52 +00:00
Makefile	DONT_BUILD_RELINKED is gone and implied by BUILD_ARCHIVE now	2005-10-24 02:26:13 +00:00
TransformInternals.cpp	Remove dead #include	2005-10-29 04:41:30 +00:00
TransformInternals.h	ConvertibleToGEP always returns 0, remove some old crufty code which	2005-07-26 16:38:28 +00:00