Skip to content
Commit 322c826c authored by Chris Lattner's avatar Chris Lattner
Browse files

Fix two problems in SelectionDAGLegalize::ExpandBUILD_VECTOR's handling

of BUILD_VECTORS that only have two unique elements:

1. The previous code was nondeterminstic, because it walked a map in
   SDOperand order, which isn't determinstic.
2. The previous code didn't handle the case when one element was undef
   very well.  Now we ensure that the generated shuffle mask has the
   undef vector on the RHS (instead of potentially being on the LHS)
   and that any elements that refer to it are themselves undef.  This
   allows us to compile CodeGen/X86/vec_set-9.ll into:

_test3:
	movd	%rdi, %xmm0
	punpcklqdq	%xmm0, %xmm0
	ret

instead of:

_test3:
	movd	%rdi, %xmm1
	#IMPLICIT_DEF %xmm0
	punpcklqdq	%xmm1, %xmm0
	ret

... saving a register.

llvm-svn: 48060
parent a1f25b00
Loading
Loading
Loading
Loading
0% Loading or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment