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Fix SCEV denormalization of expressions where the exit value from
one loop is involved in the increment of an addrec for another loop. This fixes rdar://8168938. llvm-svn: 108863
This commit is contained in:
Dan Gohman
parent
e5f3371961
commit
45ba7b5c5c
@ -45,7 +45,7 @@ static bool IVUseShouldUsePostIncValue(Instruction *User, Value *Operand,
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// their uses occur in the predecessor block, not the block the PHI lives in)
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// should still use the post-inc value. Check for this case now.
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PHINode *PN = dyn_cast<PHINode>(User);
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if (!PN) return false; // not a phi, not dominated by latch block.
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if (!PN || !Operand) return false; // not a phi, not dominated by latch block.
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// Look at all of the uses of Operand by the PHI node. If any use corresponds
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// to a block that is not dominated by the latch block, give up and use the
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@ -84,6 +84,59 @@ const SCEV *llvm::TransformForPostIncUse(TransformKind Kind,
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return S;
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}
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if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
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// An addrec. This is the interesting part.
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SmallVector<const SCEV *, 8> Operands;
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const Loop *L = AR->getLoop();
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// The addrec conceptually uses its operands at loop entry.
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Instruction *LUser = L->getHeader()->begin();
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// Transform each operand.
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for (SCEVNAryExpr::op_iterator I = AR->op_begin(), E = AR->op_end();
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I != E; ++I) {
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const SCEV *O = *I;
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const SCEV *N = TransformForPostIncUse(Kind, O, LUser, 0, Loops, SE, DT);
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Operands.push_back(N);
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}
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const SCEV *Result = SE.getAddRecExpr(Operands, L);
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switch (Kind) {
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default: llvm_unreachable("Unexpected transform name!");
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case NormalizeAutodetect:
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if (IVUseShouldUsePostIncValue(User, OperandValToReplace, L, &DT)) {
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const SCEV *TransformedStep =
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TransformForPostIncUse(Kind, AR->getStepRecurrence(SE),
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User, OperandValToReplace, Loops, SE, DT);
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Result = SE.getMinusSCEV(Result, TransformedStep);
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Loops.insert(L);
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}
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#ifdef XDEBUG
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assert(S == TransformForPostIncUse(Denormalize, Result,
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User, OperandValToReplace,
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Loops, SE, DT) &&
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"SCEV normalization is not invertible!");
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#endif
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break;
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case Normalize:
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if (Loops.count(L)) {
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const SCEV *TransformedStep =
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TransformForPostIncUse(Kind, AR->getStepRecurrence(SE),
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User, OperandValToReplace, Loops, SE, DT);
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Result = SE.getMinusSCEV(Result, TransformedStep);
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}
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#ifdef XDEBUG
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assert(S == TransformForPostIncUse(Denormalize, Result,
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User, OperandValToReplace,
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Loops, SE, DT) &&
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"SCEV normalization is not invertible!");
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#endif
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break;
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case Denormalize:
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if (Loops.count(L))
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Result = cast<SCEVAddRecExpr>(Result)->getPostIncExpr(SE);
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break;
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}
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return Result;
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}
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if (const SCEVNAryExpr *X = dyn_cast<SCEVNAryExpr>(S)) {
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SmallVector<const SCEV *, 8> Operands;
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bool Changed = false;
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@ -96,37 +149,7 @@ const SCEV *llvm::TransformForPostIncUse(TransformKind Kind,
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Changed |= N != O;
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Operands.push_back(N);
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}
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if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
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// An addrec. This is the interesting part.
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const Loop *L = AR->getLoop();
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const SCEV *Result = SE.getAddRecExpr(Operands, L);
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switch (Kind) {
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default: llvm_unreachable("Unexpected transform name!");
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case NormalizeAutodetect:
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if (Instruction *OI = dyn_cast<Instruction>(OperandValToReplace))
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if (IVUseShouldUsePostIncValue(User, OI, L, &DT)) {
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const SCEV *TransformedStep =
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TransformForPostIncUse(Kind, AR->getStepRecurrence(SE),
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User, OperandValToReplace, Loops, SE, DT);
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Result = SE.getMinusSCEV(Result, TransformedStep);
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Loops.insert(L);
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}
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break;
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case Normalize:
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if (Loops.count(L)) {
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const SCEV *TransformedStep =
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TransformForPostIncUse(Kind, AR->getStepRecurrence(SE),
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User, OperandValToReplace, Loops, SE, DT);
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Result = SE.getMinusSCEV(Result, TransformedStep);
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}
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break;
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case Denormalize:
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if (Loops.count(L))
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Result = SE.getAddExpr(Result, AR->getStepRecurrence(SE));
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break;
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}
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return Result;
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}
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// If any operand actually changed, return a transformed result.
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if (Changed)
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switch (S->getSCEVType()) {
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case scAddExpr: return SE.getAddExpr(Operands);
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99
test/CodeGen/X86/lsr-normalization.ll
Normal file
99
test/CodeGen/X86/lsr-normalization.ll
Normal file
@ -0,0 +1,99 @@
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; RUN: llc < %s -march=x86-64 | grep div | count 1
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; rdar://8168938
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; This testcase involves SCEV normalization with the exit value from
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; one loop involved with the increment value for an addrec on another
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; loop. The expression should be properly normalized and simplified,
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; and require only a single division.
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%0 = type { %0*, %0* }
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@0 = private constant [13 x i8] c"Result: %lu\0A\00" ; <[13 x i8]*> [#uses=1]
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@1 = internal constant [5 x i8] c"Huh?\00" ; <[5 x i8]*> [#uses=1]
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define i32 @main(i32 %arg, i8** nocapture %arg1) nounwind {
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bb:
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%tmp = alloca %0, align 8 ; <%0*> [#uses=11]
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%tmp2 = bitcast %0* %tmp to i8* ; <i8*> [#uses=1]
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call void @llvm.memset.p0i8.i64(i8* %tmp2, i8 0, i64 16, i32 8, i1 false) nounwind
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%tmp3 = getelementptr inbounds %0* %tmp, i64 0, i32 0 ; <%0**> [#uses=3]
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store %0* %tmp, %0** %tmp3
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%tmp4 = getelementptr inbounds %0* %tmp, i64 0, i32 1 ; <%0**> [#uses=1]
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store %0* %tmp, %0** %tmp4
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%tmp5 = call noalias i8* @_Znwm(i64 24) nounwind ; <i8*> [#uses=2]
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%tmp6 = getelementptr inbounds i8* %tmp5, i64 16 ; <i8*> [#uses=2]
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%tmp7 = icmp eq i8* %tmp6, null ; <i1> [#uses=1]
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br i1 %tmp7, label %bb10, label %bb8
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bb8: ; preds = %bb
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%tmp9 = bitcast i8* %tmp6 to i32* ; <i32*> [#uses=1]
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store i32 1, i32* %tmp9
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br label %bb10
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bb10: ; preds = %bb8, %bb
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%tmp11 = bitcast i8* %tmp5 to %0* ; <%0*> [#uses=1]
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call void @_ZNSt15_List_node_base4hookEPS_(%0* %tmp11, %0* %tmp) nounwind
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%tmp12 = load %0** %tmp3 ; <%0*> [#uses=3]
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%tmp13 = icmp eq %0* %tmp12, %tmp ; <i1> [#uses=1]
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br i1 %tmp13, label %bb14, label %bb16
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bb14: ; preds = %bb10
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%tmp15 = call i32 @puts(i8* getelementptr inbounds ([5 x i8]* @1, i64 0, i64 0))
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br label %bb35
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bb16: ; preds = %bb16, %bb10
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%tmp17 = phi i64 [ %tmp22, %bb16 ], [ 0, %bb10 ] ; <i64> [#uses=1]
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%tmp18 = phi %0* [ %tmp20, %bb16 ], [ %tmp12, %bb10 ] ; <%0*> [#uses=1]
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%tmp19 = getelementptr inbounds %0* %tmp18, i64 0, i32 0 ; <%0**> [#uses=1]
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%tmp20 = load %0** %tmp19 ; <%0*> [#uses=2]
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%tmp21 = icmp eq %0* %tmp20, %tmp ; <i1> [#uses=1]
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%tmp22 = add i64 %tmp17, 1 ; <i64> [#uses=2]
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br i1 %tmp21, label %bb23, label %bb16
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bb23: ; preds = %bb16
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%tmp24 = udiv i64 100, %tmp22 ; <i64> [#uses=1]
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br label %bb25
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bb25: ; preds = %bb25, %bb23
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%tmp26 = phi i64 [ %tmp31, %bb25 ], [ 0, %bb23 ] ; <i64> [#uses=1]
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%tmp27 = phi %0* [ %tmp29, %bb25 ], [ %tmp12, %bb23 ] ; <%0*> [#uses=1]
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%tmp28 = getelementptr inbounds %0* %tmp27, i64 0, i32 0 ; <%0**> [#uses=1]
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%tmp29 = load %0** %tmp28 ; <%0*> [#uses=2]
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%tmp30 = icmp eq %0* %tmp29, %tmp ; <i1> [#uses=1]
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%tmp31 = add i64 %tmp26, 1 ; <i64> [#uses=2]
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br i1 %tmp30, label %bb32, label %bb25
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bb32: ; preds = %bb25
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%tmp33 = mul i64 %tmp31, %tmp24 ; <i64> [#uses=1]
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%tmp34 = call i32 (i8*, ...)* @printf(i8* getelementptr inbounds ([13 x i8]* @0, i64 0, i64 0), i64 %tmp33) nounwind
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br label %bb35
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bb35: ; preds = %bb32, %bb14
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%tmp36 = load %0** %tmp3 ; <%0*> [#uses=2]
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%tmp37 = icmp eq %0* %tmp36, %tmp ; <i1> [#uses=1]
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br i1 %tmp37, label %bb44, label %bb38
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bb38: ; preds = %bb38, %bb35
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%tmp39 = phi %0* [ %tmp41, %bb38 ], [ %tmp36, %bb35 ] ; <%0*> [#uses=2]
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%tmp40 = getelementptr inbounds %0* %tmp39, i64 0, i32 0 ; <%0**> [#uses=1]
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%tmp41 = load %0** %tmp40 ; <%0*> [#uses=2]
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%tmp42 = bitcast %0* %tmp39 to i8* ; <i8*> [#uses=1]
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call void @_ZdlPv(i8* %tmp42) nounwind
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%tmp43 = icmp eq %0* %tmp41, %tmp ; <i1> [#uses=1]
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br i1 %tmp43, label %bb44, label %bb38
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bb44: ; preds = %bb38, %bb35
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ret i32 0
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}
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declare i32 @printf(i8* nocapture, ...) nounwind
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declare void @_ZNSt15_List_node_base4hookEPS_(%0*, %0*)
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declare noalias i8* @_Znwm(i64)
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declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) nounwind
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declare void @_ZdlPv(i8*) nounwind
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declare i32 @puts(i8* nocapture) nounwind
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