From 8da94ad6e0947690201c543da556ec0396ad9912 Mon Sep 17 00:00:00 2001 From: Hal Finkel Date: Tue, 7 Aug 2012 17:04:20 +0000 Subject: [PATCH] Add a comment about mftb vs. mfspr on PPC. Thanks to Alex Rosenberg for the suggestion. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161428 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/PowerPC/PPCInstr64Bit.td | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/lib/Target/PowerPC/PPCInstr64Bit.td b/lib/Target/PowerPC/PPCInstr64Bit.td index 5df735aaba7..39778a5dc1e 100644 --- a/lib/Target/PowerPC/PPCInstr64Bit.td +++ b/lib/Target/PowerPC/PPCInstr64Bit.td @@ -269,6 +269,10 @@ let Pattern = [(set G8RC:$rT, readcyclecounter)] in def MFTB8 : XFXForm_1_ext<31, 339, 268, (outs G8RC:$rT), (ins), "mfspr $rT, 268", SprMFTB>, PPC970_DGroup_First, PPC970_Unit_FXU; +// Note that encoding mftb using mfspr is now the preferred form, +// and has been since at least ISA v2.03. The mftb instruction has +// now been phased out. Using mfspr, however, is known not to work on +// the POWER3. let Defs = [X1], Uses = [X1] in def DYNALLOC8 : Pseudo<(outs G8RC:$result), (ins G8RC:$negsize, memri:$fpsi),"", -- 2.34.1