Displaying 3 results from an estimated 3 matches for "selectphinod".
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selectphinodes
2004 Jul 08
0
[LLVMdev] PHI nodes in machine code
On Thu, Jul 08, 2004 at 08:06:29PM +0400, Vladimir Prus wrote:
> Could anybody quickly explain why PHI nodes instructions are necessary
> in machine code? And why the code in LiveVariables.cpp which looks at
> those PHI nodes (line 249 and below) is necessary.
LLVM Machine code is in SSA.
Let's say you want to do
r = a cond b
But doing this:
if (a cond b) then
r = 1
2004 Jul 09
2
[LLVMdev] PHI nodes in machine code
...ns that operand0 and operand1 (the successor basic blocks)
> > suddenly get more predecessor than recorded in phi nodes, and
> > LiveVariables.cpp asserts on that.
>
> Naturally, as PHI nodes need to have as many entries as there are
> predecessors.
Ehmm... this means the 'SelectPHINodes' function I've copy-pasted from X86
backend needs more work... gotta do that now.
- Volodya
2004 Jul 08
4
[LLVMdev] PHI nodes in machine code
Could anybody quickly explain why PHI nodes instructions are necessary in
machine code? And why the code in LiveVariables.cpp which looks at those PHI
nodes (line 249 and below) is necessary.
The reason I'm asking is that I try to support 64-bit comparison and I do it
by generating code like:
// if high1 cond high2: goto operand0
// if high1 reverse_cond high2: