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author | xleroy <xleroy@fca1b0fc-160b-0410-b1d3-a4f43f01ea2e> | 2013-07-29 12:10:11 +0000 |
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committer | xleroy <xleroy@fca1b0fc-160b-0410-b1d3-a4f43f01ea2e> | 2013-07-29 12:10:11 +0000 |
commit | 41b7ecb127b93b1aecc29a298ec21dc94603e6fa (patch) | |
tree | 287ce1cbf88caf973534715c7816d57b9089b265 /ia32/Asm.v | |
parent | 4bf8b331372388dc9cb39154c986c918df9e071c (diff) | |
download | compcert-41b7ecb127b93b1aecc29a298ec21dc94603e6fa.tar.gz compcert-41b7ecb127b93b1aecc29a298ec21dc94603e6fa.zip |
Optimize integer divisions by positive constants, turning them into
multiply-high and shifts.
git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2300 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e
Diffstat (limited to 'ia32/Asm.v')
-rw-r--r-- | ia32/Asm.v | 8 |
1 files changed, 8 insertions, 0 deletions
@@ -145,6 +145,8 @@ Inductive instruction: Type := | Psub_rr (rd: ireg) (r1: ireg) | Pimul_rr (rd: ireg) (r1: ireg) | Pimul_ri (rd: ireg) (n: int) + | Pimul_r (r1: ireg) + | Pmul_r (r1: ireg) | Pdiv (r1: ireg) | Pidiv (r1: ireg) | Pand_rr (rd: ireg) (r1: ireg) @@ -540,6 +542,12 @@ Definition exec_instr (c: code) (i: instruction) (rs: regset) (m: mem) : outcome Next (nextinstr_nf (rs#rd <- (Val.mul rs#rd rs#r1))) m | Pimul_ri rd n => Next (nextinstr_nf (rs#rd <- (Val.mul rs#rd (Vint n)))) m + | Pimul_r r1 => + Next (nextinstr_nf (rs#EAX <- (Val.mul rs#EAX rs#r1) + #EDX <- (Val.mulhs rs#EAX rs#r1))) m + | Pmul_r r1 => + Next (nextinstr_nf (rs#EAX <- (Val.mul rs#EAX rs#r1) + #EDX <- (Val.mulhu rs#EAX rs#r1))) m | Pdiv r1 => let vn := rs#EAX in let vd := (rs#EDX <- Vundef)#r1 in match Val.divu vn vd, Val.modu vn vd with |