[PATCH] D15604: Changes in conversion cost model for X86 target

Demikhovsky, Elena via llvm-commits llvm-commits at lists.llvm.org
Mon Dec 21 10:35:18 PST 2015

The current cost model gives cost 40.
The new model gives 3.

This is the real code (SSE2)
sitofpv4i32v4double:                    # @sitofpv4i32v4double
# BB#0:
        cvtdq2pd        %xmm0, %xmm2
        pshufd  $78, %xmm0, %xmm0       # xmm0 = xmm0[2,3,0,1]
        cvtdq2pd        %xmm0, %xmm1
        movaps  %xmm2, %xmm0
-  Elena

-----Original Message-----
From: Nadav Rotem [mailto:nrotem at apple.com] 
Sent: Monday, December 21, 2015 19:01
To: Demikhovsky, Elena <elena.demikhovsky at intel.com>; hfinkel at anl.gov; Andrea_DiBiagio at sn.scee.net; nrotem at apple.com; congh at google.com; Nuzman, Dorit <dorit.nuzman at intel.com>
Cc: llvm-commits at lists.llvm.org
Subject: Re: [PATCH] D15604: Changes in conversion cost model for X86 target

nadav added a comment.


We don't let the instruction Sitofp <4 x i32 > %a to <4 x f64> go through the type legalizer.

We handle it as a DAGCombine optimization.  DAGCombine optimizations are represented as entries in the table.




Intel Israel (74) Limited

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