6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-09-30 04:56:49 +00:00
Code Issues Projects Releases Wiki Activity

When forgetting SCEVs for loop PHIs, don't forget SCEVUnknown values.

Browse Source 
These values aren't analyzable, so they don't care if more information
about the loop trip count can be had. Also, SCEVUnknown is used for
a PHI while the PHI itself is being analyzed, so it needs to be left
in the Scalars map. This fixes a variety of subtle issues.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71533 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-05-12 01:27:58 +00:00
parent 42a5875e10
commit efb9fbfdab
2 changed files with 44 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
lib/Analysis/ScalarEvolution.cpp
View File

@ -2309,10 +2309,20 @@ void ScalarEvolution::forgetLoopBackedgeTakenCount(const Loop *L) {
void ScalarEvolution::forgetLoopPHIs(const Loop *L) {
BasicBlock *Header = L->getHeader();
// Push all Loop-header PHIs onto the Worklist stack, except those
// that are presently represented via a SCEVUnknown. SCEVUnknown for
// a PHI either means that it has an unrecognized structure, or it's
// a PHI that's in the progress of being computed by createNodeForPHI.
// In the former case, additional loop trip count information isn't
// going to change anything. In the later case, createNodeForPHI will
// perform the necessary updates on its own when it gets to that point.
SmallVector<Instruction *, 16> Worklist;
for (BasicBlock::iterator I = Header->begin();
PHINode *PN = dyn_cast<PHINode>(I); ++I)
Worklist.push_back(PN);
PHINode *PN = dyn_cast<PHINode>(I); ++I) {
std::map<SCEVCallbackVH, SCEVHandle>::iterator It = Scalars.find((Value*)I);
if (It != Scalars.end() && !isa<SCEVUnknown>(It->second))
Worklist.push_back(PN);
}
while (!Worklist.empty()) {
Instruction *I = Worklist.pop_back_val();

32
test/Transforms/IndVarSimplify/loop_evaluate_5.ll Normal file
View File

@ -0,0 +1,32 @@
; RUN: llvm-as < %s | opt -indvars | llvm-dis | grep {120, %bb2.bb3_crit_edge}
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64"
target triple = "i686-pc-linux-gnu"
; Indvars should be able to compute an exit value for %tmp1.
define i32 @testcase(i5 zeroext %k) nounwind readnone {
entry:
br i1 false, label %bb3, label %bb.nph
bb.nph: ; preds = %entry
br label %bb
bb: ; preds = %bb2, %bb.nph
%result2 = phi i32 [ %tmp1, %bb2 ], [ 0, %bb.nph ] ; <i32> [#uses=1]
%k_01 = phi i5 [ %indvar_next1, %bb2 ], [ 0, %bb.nph ] ; <i5> [#uses=2]
%tmp2 = zext i5 %k_01 to i32 ; <i32> [#uses=1]
%tmp1 = add i32 %tmp2, %result2 ; <i32> [#uses=2]
%indvar_next1 = add i5 %k_01, 1 ; <i5> [#uses=2]
br label %bb2
bb2: ; preds = %bb
%phitmp = icmp eq i5 %indvar_next1, -16 ; <i1> [#uses=1]
br i1 %phitmp, label %bb2.bb3_crit_edge, label %bb
bb2.bb3_crit_edge: ; preds = %bb2
br label %bb3
bb3: ; preds = %bb2.bb3_crit_edge, %entry
%result.lcssa = phi i32 [ %tmp1, %bb2.bb3_crit_edge ], [ 0, %entry ] ; <i32> [#uses=1]
ret i32 %result.lcssa
}