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...(int s) { int * p = malloc(s * sizeof int); ... int q = p[s - 2]; } then the access of p[s - 2] always stays in bound. I implemented a prototype using the Scalar Evolution pass. Here are the pseudo-code of the implementation: const SCEV * offset = SE->getMinusSCEV(SE->getSCEV(GEP), GEPBase); const SCEV * bounds = SE->getSCEV(objSize); if (SE->getSMaxExpr(offset, bounds) == bounds) { ++safeGEPs; } But it turns out that SCEVSMaxExpr does not handle the case of SMax(N, N-2). My question is, is there a plan to support something like this, or is it possible to do some...

...; } > > > > then the access of p[s - 2] always stays in bound. > > > > I implemented a prototype using the Scalar Evolution pass. Here are the > > pseudo-code of the implementation: > > > > const SCEV * offset = SE->getMinusSCEV(SE->getSCEV(GEP), GEPBase); > > const SCEV * bounds = SE->getSCEV(objSize); > > > > if (SE->getSMaxExpr(offset, bounds) == bounds) { > > ++safeGEPs; > > } > > > > But it turns out that SCEVSMaxExpr does not handle the case of SMax(N, > > N-2). > > Con...

...... > int q = p[s - 2]; > } > > then the access of p[s - 2] always stays in bound. > > I implemented a prototype using the Scalar Evolution pass. Here are the > pseudo-code of the implementation: > > const SCEV * offset = SE->getMinusSCEV(SE->getSCEV(GEP), GEPBase); > const SCEV * bounds = SE->getSCEV(objSize); > > if (SE->getSMaxExpr(offset, bounds) == bounds) { > ++safeGEPs; > } > > But it turns out that SCEVSMaxExpr does not handle the case of SMax(N, > N-2). Consider 8-bit integers and N = -127. N-1 equals INT_...

Now that icmp and fcmp have supported returning vectors of i1 for a while, I think it's time to remove the vicmp and vfcmp instructions from LLVM. The good news is that we've never shipped a release that included them so we won't be providing auto-upgrade support. There is some existing backend support for vicmp and vfcmp that looks different from what icmp and fcmp do. If this

...then the access of p[s - 2] always stays in bound. > > > > > > I implemented a prototype using the Scalar Evolution pass. Here are the > > > pseudo-code of the implementation: > > > > > > const SCEV * offset = SE->getMinusSCEV(SE->getSCEV(GEP), GEPBase); > > > const SCEV * bounds = SE->getSCEV(objSize); > > > > > > if (SE->getSMaxExpr(offset, bounds) == bounds) { > > > ++safeGEPs; > > > } > > > > > > But it turns out that SCEVSMaxExpr does not handle the case of SMa...

...access of p[s - 2] always stays in bound. >>>> >>>> I implemented a prototype using the Scalar Evolution pass. Here are the >>>> pseudo-code of the implementation: >>>> >>>> const SCEV * offset = SE->getMinusSCEV(SE->getSCEV(GEP), GEPBase); >>>> const SCEV * bounds = SE->getSCEV(objSize); >>>> >>>> if (SE->getSMaxExpr(offset, bounds) == bounds) { >>>> ++safeGEPs; >>>> } >>>> >>>> But it turns out that SCEVSMaxExpr does not handle th...