diff options
Diffstat (limited to 'lib/Target/X86/README-SSE.txt')
| -rw-r--r-- | lib/Target/X86/README-SSE.txt | 78 |
1 files changed, 0 insertions, 78 deletions
diff --git a/lib/Target/X86/README-SSE.txt b/lib/Target/X86/README-SSE.txt index 71329b0..e6896e8 100644 --- a/lib/Target/X86/README-SSE.txt +++ b/lib/Target/X86/README-SSE.txt @@ -93,36 +93,6 @@ The pattern isel got this one right. //===---------------------------------------------------------------------===// -SSE should implement 'select_cc' using 'emulated conditional moves' that use -pcmp/pand/pandn/por to do a selection instead of a conditional branch: - -double %X(double %Y, double %Z, double %A, double %B) { - %C = setlt double %A, %B - %z = fadd double %Z, 0.0 ;; select operand is not a load - %D = select bool %C, double %Y, double %z - ret double %D -} - -We currently emit: - -_X: - subl $12, %esp - xorpd %xmm0, %xmm0 - addsd 24(%esp), %xmm0 - movsd 32(%esp), %xmm1 - movsd 16(%esp), %xmm2 - ucomisd 40(%esp), %xmm1 - jb LBB_X_2 -LBB_X_1: - movsd %xmm0, %xmm2 -LBB_X_2: - movsd %xmm2, (%esp) - fldl (%esp) - addl $12, %esp - ret - -//===---------------------------------------------------------------------===// - Lower memcpy / memset to a series of SSE 128 bit move instructions when it's feasible. @@ -787,25 +757,6 @@ cheaper to do fld1 than load from a constant pool for example, so //===---------------------------------------------------------------------===// -The X86 backend should be able to if-convert SSE comparisons like "ucomisd" to -"cmpsd". For example, this code: - -double d1(double x) { return x == x ? x : x + x; } - -Compiles into: - -_d1: - ucomisd %xmm0, %xmm0 - jnp LBB1_2 - addsd %xmm0, %xmm0 - ret -LBB1_2: - ret - -Also, the 'ret's should be shared. This is PR6032. - -//===---------------------------------------------------------------------===// - These should compile into the same code (PR6214): Perhaps instcombine should canonicalize the former into the later? @@ -858,35 +809,6 @@ doing a shuffle from v[1] to v[0] then a float store. //===---------------------------------------------------------------------===// -On SSE4 machines, we compile this code: - -define <2 x float> @test2(<2 x float> %Q, <2 x float> %R, - <2 x float> *%P) nounwind { - %Z = fadd <2 x float> %Q, %R - - store <2 x float> %Z, <2 x float> *%P - ret <2 x float> %Z -} - -into: - -_test2: ## @test2 -## BB#0: - insertps $0, %xmm2, %xmm2 - insertps $16, %xmm3, %xmm2 - insertps $0, %xmm0, %xmm3 - insertps $16, %xmm1, %xmm3 - addps %xmm2, %xmm3 - movq %xmm3, (%rdi) - movaps %xmm3, %xmm0 - pshufd $1, %xmm3, %xmm1 - ## kill: XMM1<def> XMM1<kill> - ret - -The insertps's of $0 are pointless complex copies. - -//===---------------------------------------------------------------------===// - [UNSAFE FP] void foo(double, double, double); |