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author | Evan Cheng <evan.cheng@apple.com> | 2006-11-10 22:03:35 +0000 |
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committer | Evan Cheng <evan.cheng@apple.com> | 2006-11-10 22:03:35 +0000 |
commit | a8d39be75b63961962482ed3a5c10790b8911a0b (patch) | |
tree | 6bee4054f67d69f951900c031e4fccdf5add138a /lib/Target/X86/README-SSE.txt | |
parent | 8ca29326e19201075f6dc95781560ea9ad41ecec (diff) | |
download | external_llvm-a8d39be75b63961962482ed3a5c10790b8911a0b.zip external_llvm-a8d39be75b63961962482ed3a5c10790b8911a0b.tar.gz external_llvm-a8d39be75b63961962482ed3a5c10790b8911a0b.tar.bz2 |
These are done.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31649 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Target/X86/README-SSE.txt')
-rw-r--r-- | lib/Target/X86/README-SSE.txt | 58 |
1 files changed, 0 insertions, 58 deletions
diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt index 2de68ed..5c7722d 100644 --- a/lib/Target/X86/README-SSE.txt +++ b/lib/Target/X86/README-SSE.txt @@ -4,30 +4,6 @@ //===---------------------------------------------------------------------===// -There are serious issues folding loads into "scalar sse" intrinsics. For -example, this: - -float minss4( float x, float *y ) { - return _mm_cvtss_f32(_mm_min_ss(_mm_set_ss(x),_mm_set_ss(*y))); -} - -compiles to: - -_minss4: - subl $4, %esp - movl 12(%esp), %eax -*** movss 8(%esp), %xmm0 -*** movss (%eax), %xmm1 -*** minss %xmm1, %xmm0 - movss %xmm0, (%esp) - flds (%esp) - addl $4, %esp - ret - -Each operand of the minss is a load. At least one should be folded! - -//===---------------------------------------------------------------------===// - Expand libm rounding functions inline: Significant speedups possible. http://gcc.gnu.org/ml/gcc-patches/2006-10/msg00909.html @@ -165,17 +141,6 @@ This will be solved when we go to a dynamic programming based isel. //===---------------------------------------------------------------------===// -Should generate min/max for stuff like: - -void minf(float a, float b, float *X) { - *X = a <= b ? a : b; -} - -Make use of floating point min / max instructions. Perhaps introduce ISD::FMIN -and ISD::FMAX node types? - -//===---------------------------------------------------------------------===// - Lower memcpy / memset to a series of SSE 128 bit move instructions when it's feasible. @@ -225,29 +190,6 @@ Perhaps use pxor / xorp* to clear a XMM register first? //===---------------------------------------------------------------------===// -Better codegen for: - -void f(float a, float b, vector float * out) { *out = (vector float){ a, 0.0, 0.0, b}; } -void f(float a, float b, vector float * out) { *out = (vector float){ a, b, 0.0, 0}; } - -For the later we generate: - -_f: - pxor %xmm0, %xmm0 - movss 8(%esp), %xmm1 - movaps %xmm0, %xmm2 - unpcklps %xmm1, %xmm2 - movss 4(%esp), %xmm1 - unpcklps %xmm0, %xmm1 - unpcklps %xmm2, %xmm1 - movl 12(%esp), %eax - movaps %xmm1, (%eax) - ret - -This seems like it should use shufps, one for each of a & b. - -//===---------------------------------------------------------------------===// - How to decide when to use the "floating point version" of logical ops? Here are some code fragments: |