<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Mar 2, 2015, at 1:19 PM, Tom Stellard <<a href="mailto:tom@stellard.net" class="">tom@stellard.net</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">On Mon, Mar 02, 2015 at 10:14:00PM +0100, Marek Olšák wrote:</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">On Mon, Mar 2, 2015 at 10:05 PM, Tom Stellard <<a href="mailto:tom@stellard.net" class="">tom@stellard.net</a>> wrote:<br class=""><blockquote type="cite" class="">On Mon, Mar 02, 2015 at 12:54:16PM +0100, Marek Olšák wrote:<br class=""><blockquote type="cite" class="">From: Marek Olšák <<a href="mailto:marek.olsak@amd.com" class="">marek.olsak@amd.com</a>><br class=""><br class="">---<br class="">src/gallium/drivers/radeonsi/si_shader.c | 22 ++++++++++++++++------<br class="">1 file changed, 16 insertions(+), 6 deletions(-)<br class=""><br class="">diff --git a/src/gallium/drivers/radeonsi/si_shader.c b/src/gallium/drivers/radeonsi/si_shader.c<br class="">index b0417ed..f125483 100644<br class="">--- a/src/gallium/drivers/radeonsi/si_shader.c<br class="">+++ b/src/gallium/drivers/radeonsi/si_shader.c<br class="">@@ -192,6 +192,20 @@ static int get_param_index(unsigned semantic_name, unsigned index,<br class="">}<br class=""><br class="">/**<br class="">+ * BitField Extract: ((value >> rshift) & ((1 << bitwidth) - 1))<br class="">+ */<br class=""></blockquote><br class="">Ideally, we would just add a pattern for this in the backend and emit generic<br class="">LLVM IR here. This would also make it possible to share the code with llvmpipe.<br class=""><br class="">I think the best place to do this would be in AMDGPUTargetLowering::performDAGCombine().<br class=""></blockquote><br class="">Why not SIInstructions.td?<br class=""><br class=""></blockquote><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">Because for patterns like this, I think it is important to match them as</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">early as possible, because there may be another optimization which reduces</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">the sequence from 5 to 4 instructions which would cause the pattern not to match.</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">-Tom</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""></div></blockquote></div><br class=""><div class=""><br class=""></div><div class="">I think the opposite in this case. The basic bit operations have a lot of existing combines on them, and the computeKnownBits implementations are more complete. The BFE nodes are not as well understood, and trickier to deal with. AArch64 and NVPTX both have essentially the same instruction, and they have a large bit of code to match them in their ISelDAGToDAGs. I’ve wanted to add a generic BFE node to be matched after legalization, but I haven’t had time to do it.</div><div class=""><br class=""></div><div class="">-Matt</div></body></html>