search for: mtlo

...t think making mthi/lo clobber the other half would work. For example, this is an illegal sequence of instructions, where instruction 3 makes $hi unpredictable: 1. mult $lo<def>, $hi<def>, $2, $3 // $lo<def>, $hi<def> = $2 * $3 2. mflo $4, $lo<use> // $4 <- $lo 3. mtlo $lo<def>, $6 // $lo <- $6. effectively clobbers $hi too. 4. mfhi $5, $hi<use> // $5 <- $hi 5. mthi $hi<def>, $7 // $hi <- $7 6. madd $lo<def>, $hi<def>, $8, $9, $lo<use>, $hi<use> // $lo<def>, $hi<def> = $2 * $3 + (lo,hi) Unlike the mt...

...rent RA framework I think. > > For example, this is an illegal sequence of instructions, where instruction 3 makes $hi unpredictable: > > 1. mult $lo<def>, $hi<def>, $2, $3 // $lo<def>, $hi<def> = $2 * $3 > 2. mflo $4, $lo<use> // $4 <- $lo > 3. mtlo $lo<def>, $6 // $lo <- $6. effectively clobbers $hi too. > 4. mfhi $5, $hi<use> // $5 <- $hi > 5. mthi $hi<def>, $7 // $hi <- $7 > 6. madd $lo<def>, $hi<def>, $8, $9, $lo<use>, $hi<use> // $lo<def>, $hi<def> = $2 * $3 + (lo,hi)...

Currently it will always spill / restore the whole vreg but only spilling the parts that are actually live would be a nice addition in the future. Looking at r192119': if "mtlo" writes to $LO and sets $HI to an unpredictable value, then it should just have an additional (dead) def operand for $hi, shouldn't it? Greetings Matthias Am 10/8/13, 11:03 AM, schrieb Akira Hatanaka: > Hi, > > I have a question about the way sub-registers are spilled and...

...mporary integer GPR that is used during pseudo-expansion. This is what happens during pseudo-expansion: The following pseudo LoadAC $acc, FI // Pseudo load instructions. Load from FI to accumulator $acc. is expanded into this sequence: LW $reg, FI // load from FI to temporary GPR $reg MTLO $reg // copy $reg to register LO LW $reg, FI + 4 // load from FI+4 to GPR $reg MTHI $reg // copy $reg to register HI -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20130325/d05b1990/attachme...

...t; > This is what happens during pseudo-expansion: > > The following pseudo > > LoadAC $acc, FI // Pseudo load instructions. Load from FI to accumulator $acc. > > > is expanded into this sequence: > > LW $reg, FI // load from FI to temporary GPR $reg > MTLO $reg // copy $reg to register LO > LW $reg, FI + 4 // load from FI+4 to GPR $reg > MTHI $reg // copy $reg to register HI Hi Akira, The register scavenger is not really supposed to be used in more than one pass, because you would need to allocate a separate emergency spill...

...ion: > > > > The following pseudo > > > > LoadAC $acc, FI // Pseudo load instructions. Load from FI to accumulator > $acc. > > > > > > is expanded into this sequence: > > > > LW $reg, FI // load from FI to temporary GPR $reg > > MTLO $reg // copy $reg to register LO > > LW $reg, FI + 4 // load from FI+4 to GPR $reg > > MTHI $reg // copy $reg to register HI > > Hi Akira, > > The register scavenger is not really supposed to be used in more than one > pass, because you would need to al...