diff options
| -rw-r--r-- | lib/Analysis/ScalarEvolution.cpp | 13 | ||||
| -rw-r--r-- | test/Analysis/ScalarEvolution/nsw.ll | 40 |
2 files changed, 47 insertions, 6 deletions
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp index ca959ab..227f1de 100644 --- a/lib/Analysis/ScalarEvolution.cpp +++ b/lib/Analysis/ScalarEvolution.cpp @@ -3088,15 +3088,20 @@ const SCEV *ScalarEvolution::createNodeForPHI(PHINode *PN) { Flags = setFlags(Flags, SCEV::FlagNUW); if (OBO->hasNoSignedWrap()) Flags = setFlags(Flags, SCEV::FlagNSW); - } else if (const GEPOperator *GEP = - dyn_cast<GEPOperator>(BEValueV)) { + } else if (GEPOperator *GEP = dyn_cast<GEPOperator>(BEValueV)) { // If the increment is an inbounds GEP, then we know the address // space cannot be wrapped around. We cannot make any guarantee // about signed or unsigned overflow because pointers are // unsigned but we may have a negative index from the base - // pointer. - if (GEP->isInBounds()) + // pointer. We can guarantee that no unsigned wrap occurs if the + // indices form a positive value. + if (GEP->isInBounds()) { Flags = setFlags(Flags, SCEV::FlagNW); + + const SCEV *Ptr = getSCEV(GEP->getPointerOperand()); + if (isKnownPositive(getMinusSCEV(getSCEV(GEP), Ptr))) + Flags = setFlags(Flags, SCEV::FlagNUW); + } } const SCEV *StartVal = getSCEV(StartValueV); diff --git a/test/Analysis/ScalarEvolution/nsw.ll b/test/Analysis/ScalarEvolution/nsw.ll index 659cf4f..05992ea 100644 --- a/test/Analysis/ScalarEvolution/nsw.ll +++ b/test/Analysis/ScalarEvolution/nsw.ll @@ -62,11 +62,11 @@ for.body.lr.ph.i.i: ; preds = %entry for.body.i.i: ; preds = %for.body.i.i, %for.body.lr.ph.i.i %__first.addr.02.i.i = phi i32* [ %begin, %for.body.lr.ph.i.i ], [ %ptrincdec.i.i, %for.body.i.i ] ; CHECK: %__first.addr.02.i.i -; CHECK-NEXT: --> {%begin,+,4}<nw><%for.body.i.i> +; CHECK-NEXT: --> {%begin,+,4}<nuw><%for.body.i.i> store i32 0, i32* %__first.addr.02.i.i, align 4 %ptrincdec.i.i = getelementptr inbounds i32* %__first.addr.02.i.i, i64 1 ; CHECK: %ptrincdec.i.i -; CHECK-NEXT: --> {(4 + %begin),+,4}<nw><%for.body.i.i> +; CHECK-NEXT: --> {(4 + %begin),+,4}<nuw><%for.body.i.i> %cmp.i.i = icmp eq i32* %ptrincdec.i.i, %end br i1 %cmp.i.i, label %for.cond.for.end_crit_edge.i.i, label %for.body.i.i @@ -122,3 +122,39 @@ exit: %result = phi i32 [ %a, %entry ], [ %tmp2, %greater ] ret i32 %result } + +; TODO: This could fold down to '1' +; CHECK-LABEL: PR12375 +; CHECK: --> {(4 + %arg),+,4}<nuw><%bb1> Exits: (4 + (4 * ((-1 + (-1 * %arg) + ((4 + %arg) umax (8 + %arg)<nsw>)) /u 4)) + %arg) +define i32 @PR12375(i32* readnone %arg) { +bb: + %tmp = getelementptr inbounds i32* %arg, i64 2 + br label %bb1 + +bb1: ; preds = %bb1, %bb + %tmp2 = phi i32* [ %arg, %bb ], [ %tmp5, %bb1 ] + %tmp3 = phi i32 [ 0, %bb ], [ %tmp4, %bb1 ] + %tmp4 = add nsw i32 %tmp3, 1 + %tmp5 = getelementptr inbounds i32* %tmp2, i64 1 + %tmp6 = icmp ult i32* %tmp5, %tmp + br i1 %tmp6, label %bb1, label %bb7 + +bb7: ; preds = %bb1 + ret i32 %tmp4 +} + +; CHECK-LABEL: PR12376 +; CHECK: --> {(4 + %arg),+,4}<nuw><%bb2> Exits: (4 + (4 * ((3 + (-1 * %arg) + (%arg umax %arg1)) /u 4)) + %arg) +define void @PR12376(i32* nocapture %arg, i32* nocapture %arg1) { +bb: + br label %bb2 + +bb2: ; preds = %bb2, %bb + %tmp = phi i32* [ %arg, %bb ], [ %tmp4, %bb2 ] + %tmp3 = icmp ult i32* %tmp, %arg1 + %tmp4 = getelementptr inbounds i32* %tmp, i64 1 + br i1 %tmp3, label %bb2, label %bb5 + +bb5: ; preds = %bb2 + ret void +} |