//===---------------------------------------------------------------------===//
-SSE4 extract-to-mem ops aren't being pattern matched because of the AssertZext
-sitting between the truncate and the extract.
-
-//===---------------------------------------------------------------------===//
-
INSERTPS can match any insert (extract, imm1), imm2 for 4 x float, and insert
any number of 0.0 simultaneously. Currently we only use it for simple
insertions.
//===---------------------------------------------------------------------===//
-'select' on vectors and scalars could be a whole lot better. We currently
-lower them to conditional branches. On x86-64 for example, we compile this:
-
-double test(double a, double b, double c, double d) { return a<b ? c : d; }
-
-to:
-
-_test:
- ucomisd %xmm0, %xmm1
- ja LBB1_2 # entry
-LBB1_1: # entry
- movapd %xmm3, %xmm2
-LBB1_2: # entry
- movapd %xmm2, %xmm0
- ret
-
-instead of:
-
-_test:
- cmpltsd %xmm1, %xmm0
- andpd %xmm0, %xmm2
- andnpd %xmm3, %xmm0
- orpd %xmm2, %xmm0
- ret
-
-For unpredictable branches, the later is much more efficient. This should
-just be a matter of having scalar sse map to SELECT_CC and custom expanding
-or iseling it.
-
-//===---------------------------------------------------------------------===//
-
LLVM currently generates stack realignment code, when it is not necessary
needed. The problem is that we need to know about stack alignment too early,
before RA runs.