diff options
Diffstat (limited to 'backend/PPC.v')
| -rw-r--r-- | backend/PPC.v | 31 |
1 files changed, 29 insertions, 2 deletions
diff --git a/backend/PPC.v b/backend/PPC.v index 7a330639..cfd07405 100644 --- a/backend/PPC.v +++ b/backend/PPC.v @@ -125,7 +125,8 @@ Inductive instruction : Set := | Pfabs: freg -> freg -> instruction (**r float absolute value *) | Pfadd: freg -> freg -> freg -> instruction (**r float addition *) | Pfcmpu: freg -> freg -> instruction (**r float comparison *) - | Pfcti: ireg -> freg -> instruction (**r float-to-int conversion *) + | Pfcti: ireg -> freg -> instruction (**r float-to-signed-int conversion *) + | Pfctiu: ireg -> freg -> instruction (**r float-to-unsigned-int conversion *) | Pfdiv: freg -> freg -> freg -> instruction (**r float division *) | Pfmadd: freg -> freg -> freg -> freg -> instruction (**r float multiply-add *) | Pfmr: freg -> freg -> instruction (**r float move *) @@ -199,7 +200,7 @@ lbl: .double floatcst >> Initialized data in the constant data section are not modeled here, which is why we use a pseudo-instruction for this purpose. -- [Pfcti]: convert a float to an integer. This requires a transfer +- [Pfcti]: convert a float to a signed integer. This requires a transfer via memory of a 32-bit integer from a float register to an int register, which our memory model cannot express. Expands to: << @@ -208,6 +209,30 @@ lbl: .double floatcst lwz rdst, 4(r1) addi r1, r1, 8 >> +- [Pfctiu]: convert a float to an unsigned integer. The PowerPC way + to do this is to compare the argument against the floating-point + constant [2^31], subtract [2^31] if bigger, then convert to a signed + integer as above, then add back [2^31] if needed. Expands to: +<< + addis r2, 0, ha16(lbl1) + lfd f13, lo16(lbl1)(r2) + fcmpu cr7, rsrc, f13 + cror 30, 29, 30 + beq cr7, lbl2 + fctiwz f13, rsrc + stfdu f13, -8(r1) + lwz rdst, 4(r1) + b lbl3 +lbl2: fsub f13, rsrc, f13 + fctiwz f13, f13 + stfdu f13, -8(r1) + lwz rdst, 4(r1) + addis rdst, rdst, 0x8000 +lbl3: addi r1, r1, 8 + .const_data +lbl1: .long 0x41e00000, 0x00000000 # 2^31 in double precision + .text +>> - [Pictf]: convert a signed integer to a float. This requires complicated bit-level manipulations of IEEE floats through mixed float and integer arithmetic over a memory word, which our memory model and axiomatization @@ -611,6 +636,8 @@ Definition exec_instr (c: code) (i: instruction) (rs: regset) (m: mem) : outcome OK (nextinstr (compare_float rs rs#r1 rs#r2)) m | Pfcti rd r1 => OK (nextinstr (rs#rd <- (Val.intoffloat rs#r1) #FPR13 <- Vundef)) m + | Pfctiu rd r1 => + OK (nextinstr (rs#rd <- (Val.intuoffloat rs#r1) #FPR13 <- Vundef)) m | Pfdiv rd r1 r2 => OK (nextinstr (rs#rd <- (Val.divf rs#r1 rs#r2))) m | Pfmadd rd r1 r2 r3 => |