151997 2015-12-08 10:01:00 -0800 DFG should reduce division of a constant by a constant. 2015-12-08 10:34:26 -0800 1 1 1 Unclassified WebKit JavaScriptCore WebKit Local Build Unspecified Unspecified ASSIGNED InRadar P2 Normal --- 1 mark.lam mark.lam benjamin fpizlo ggaren keith_miller msaboff saam webkit-bug-importer oldest_to_newest 1147331 0 mark.lam 2015-12-08 10:01:00 -0800 Running LayoutTests/svg/in-html/sizing/svg-inline.html produces a scenario where we see a division of a constant by another constant: (lldb) p leftOperand (JSC::SnippetOperand) $0 = { m_resultType = (m_type = '\x05') m_type = ConstInt32 m_val = (int32Val = 600, doubleVal = 6.0841863318852727E-310, rawBits = 123145302311512) } (lldb) p rightOperand (JSC::SnippetOperand) $1 = { m_resultType = (m_type = '\x05') m_type = ConstInt32 m_val = (int32Val = 100, doubleVal = 6.0841863318605694E-310, rawBits = 123145302311012) } The DFG should have folded this into a constant int 6. 1147346 1 webkit-bug-importer 2015-12-08 10:25:26 -0800 <rdar://problem/23804458> 1147351 2 fpizlo 2015-12-08 10:34:26 -0800 Please postpone this work until we have a complete story for prediction propagation from snippets. And when you do implement this please make sure that you do it in the abstract interpreter and that the snippets continue to work even if they see constant inputs. We do not guarantee complete constant folding as a prerequisite for code generation.