[llvm] r256338 - [SCEV] Fix getLoopBackedgeTakenCounts

[Sanjoy Das via llvm-commits]

Bill Seurer wrote:
> I agree it looks broken. Several of the buildbots are failing here:
>
> /home/buildbots/ppc64be-llvm-quick/llvm-ppc64-2/llvm.src/lib/Analysis/ScalarEvolution.cpp:
> In function ‘void getLoopBackedgeTakenCounts(llvm::Loop*, VerifyMap&,
> llvm::ScalarEvolution&)’:
> /home/buildbots/ppc64be-llvm-quick/llvm-ppc64-2/llvm.src/lib/Analysis/ScalarEvolution.cpp:9456:27:
> error: use of ‘L’ before deduction of ‘auto’
> for (auto *L : reverse(*L))
> ^

JF fixed the problem in r256344.

-- Sanjoy

>
>
> On 12/23/15 12:22, JF Bastien via llvm-commits wrote:
>> Seems broken, I think r256338 fixes it.
>>
>> On Wed, Dec 23, 2015 at 9:48 AM, Sanjoy Das via llvm-commits
>> <llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>> wrote:
>>
>> Author: sanjoy
>> Date: Wed Dec 23 11:48:14 2015
>> New Revision: 256338
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=256338&view=rev
>> Log:
>> [SCEV] Fix getLoopBackedgeTakenCounts
>>
>> The way `getLoopBackedgeTakenCounts` is written right now isn't
>> correct. It will try to compute and store the BE counts of a Loop
>> #{child loop} number of times (which may be zero).
>>
>> Modified:
>> llvm/trunk/lib/Analysis/ScalarEvolution.cpp
>>
>> Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=256338&r1=256337&r2=256338&view=diff
>>
>> ==============================================================================
>>
>> --- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
>> +++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Wed Dec 23 11:48:14 2015
>> @@ -9439,23 +9439,22 @@ static void replaceSubString(std::string
>> /// getLoopBackedgeTakenCounts - Helper method for verifyAnalysis.
>> static void
>> getLoopBackedgeTakenCounts(Loop *L, VerifyMap &Map,
>> ScalarEvolution &SE) {
>> - for (Loop::reverse_iterator I = L->rbegin(), E = L->rend(); I !=
>> E; ++I) {
>> - getLoopBackedgeTakenCounts(*I, Map, SE); // recurse.
>> + std::string &S = Map[L];
>> + if (S.empty()) {
>> + raw_string_ostream OS(S);
>> + SE.getBackedgeTakenCount(L)->print(OS);
>>
>> - std::string &S = Map[L];
>> - if (S.empty()) {
>> - raw_string_ostream OS(S);
>> - SE.getBackedgeTakenCount(L)->print(OS);
>> -
>> - // false and 0 are semantically equivalent. This can happen
>> in dead loops.
>> - replaceSubString(OS.str(), "false", "0");
>> - // Remove wrap flags, their use in SCEV is highly fragile.
>> - // FIXME: Remove this when SCEV gets smarter about them.
>> - replaceSubString(OS.str(), "<nw>", "");
>> - replaceSubString(OS.str(), "<nsw>", "");
>> - replaceSubString(OS.str(), "<nuw>", "");
>> - }
>> + // false and 0 are semantically equivalent. This can happen in
>> dead loops.
>> + replaceSubString(OS.str(), "false", "0");
>> + // Remove wrap flags, their use in SCEV is highly fragile.
>> + // FIXME: Remove this when SCEV gets smarter about them.
>> + replaceSubString(OS.str(), "<nw>", "");
>> + replaceSubString(OS.str(), "<nsw>", "");
>> + replaceSubString(OS.str(), "<nuw>", "");
>> }
>> +
>> + for (auto *L : reverse(*L))
>> + getLoopBackedgeTakenCounts(L, Map, SE); // recurse.
>> }
>>
>> void ScalarEvolution::verify() const {
>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at lists.llvm.org <mailto:llvm-commits at lists.llvm.org>
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>
>>
>>
>>
>> _______________________________________________
>> llvm-commits mailing list
>> llvm-commits at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-commits
>>
>
>