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| author | Eli Friedman <eli.friedman@gmail.com> | 2010-06-03 01:16:51 +0000 |
|---|---|---|
| committer | Eli Friedman <eli.friedman@gmail.com> | 2010-06-03 01:16:51 +0000 |
| commit | a04a2c0a50f8772614070b37d2407f9df50d93bc (patch) | |
| tree | 9677588c23bf1acc777f921619204b714da2e45c | |
| parent | 2ad7e433c9aac72e290e99602bc7a68666ab52a6 (diff) | |
| download | external_llvm-a04a2c0a50f8772614070b37d2407f9df50d93bc.zip external_llvm-a04a2c0a50f8772614070b37d2407f9df50d93bc.tar.gz external_llvm-a04a2c0a50f8772614070b37d2407f9df50d93bc.tar.bz2 | |
Remove README entry which no longer compiles to something sane.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105376 91177308-0d34-0410-b5e6-96231b3b80d8
| -rw-r--r-- | lib/Target/X86/README-SSE.txt | 56 |
1 files changed, 0 insertions, 56 deletions
diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt index e5f84e8..8f2db00 100644 --- a/lib/Target/X86/README-SSE.txt +++ b/lib/Target/X86/README-SSE.txt @@ -36,62 +36,6 @@ The pattern isel got this one right. //===---------------------------------------------------------------------===// -SSE doesn't have [mem] op= reg instructions. If we have an SSE instruction -like this: - - X += y - -and the register allocator decides to spill X, it is cheaper to emit this as: - -Y += [xslot] -store Y -> [xslot] - -than as: - -tmp = [xslot] -tmp += y -store tmp -> [xslot] - -..and this uses one fewer register (so this should be done at load folding -time, not at spiller time). *Note* however that this can only be done -if Y is dead. Here's a testcase: - -@.str_3 = external global [15 x i8] -declare void @printf(i32, ...) -define void @main() { -build_tree.exit: - br label %no_exit.i7 - -no_exit.i7: ; preds = %no_exit.i7, %build_tree.exit - %tmp.0.1.0.i9 = phi double [ 0.000000e+00, %build_tree.exit ], - [ %tmp.34.i18, %no_exit.i7 ] - %tmp.0.0.0.i10 = phi double [ 0.000000e+00, %build_tree.exit ], - [ %tmp.28.i16, %no_exit.i7 ] - %tmp.28.i16 = fadd double %tmp.0.0.0.i10, 0.000000e+00 - %tmp.34.i18 = fadd double %tmp.0.1.0.i9, 0.000000e+00 - br i1 false, label %Compute_Tree.exit23, label %no_exit.i7 - -Compute_Tree.exit23: ; preds = %no_exit.i7 - tail call void (i32, ...)* @printf( i32 0 ) - store double %tmp.34.i18, double* null - ret void -} - -We currently emit: - -.BBmain_1: - xorpd %XMM1, %XMM1 - addsd %XMM0, %XMM1 -*** movsd %XMM2, QWORD PTR [%ESP + 8] -*** addsd %XMM2, %XMM1 -*** movsd QWORD PTR [%ESP + 8], %XMM2 - jmp .BBmain_1 # no_exit.i7 - -This is a bugpoint reduced testcase, which is why the testcase doesn't make -much sense (e.g. its an infinite loop). :) - -//===---------------------------------------------------------------------===// - SSE should implement 'select_cc' using 'emulated conditional moves' that use pcmp/pand/pandn/por to do a selection instead of a conditional branch: |