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-rw-r--r--compiler_and_linker/FrontEnd/Optimizer/IroEmptyLoop.c560
1 files changed, 560 insertions, 0 deletions
diff --git a/compiler_and_linker/FrontEnd/Optimizer/IroEmptyLoop.c b/compiler_and_linker/FrontEnd/Optimizer/IroEmptyLoop.c
new file mode 100644
index 0000000..23d5d4a
--- /dev/null
+++ b/compiler_and_linker/FrontEnd/Optimizer/IroEmptyLoop.c
@@ -0,0 +1,560 @@
+#include "IroEmptyLoop.h"
+#include "IroDump.h"
+#include "IroFlowgraph.h"
+#include "IroLinearForm.h"
+#include "IroLoop.h"
+#include "IroUtil.h"
+#include "IroVars.h"
+#include "compiler/CInt64.h"
+
+// forward decls
+static Boolean EmptyLoop(IRONode *fnode);
+static int CanRemoveRedundantLoop(IROLoop *loop);
+static int CanRemoveRedundantLoop1(IROLoop *loop);
+static int RedundantLoopCheck(IROLoop *loop);
+static int CheckStepOverFlow1_EmptyLoop(IROLoop *loop, CInt64 *val1, CInt64 *val2);
+static int CheckStepOverFlow2_EmptyLoop(IROLoop *loop, CInt64 *val1, CInt64 *val2);
+
+void IRO_FindEmptyLoops(void) {
+ IRONode *fnode;
+ IRONode *pred;
+ UInt16 i;
+ UInt16 x;
+
+ for (fnode = IRO_FirstNode; fnode; fnode = fnode->nextnode) {
+ x = 0;
+ for (i = 0; i < fnode->numpred; i++) {
+ pred = IRO_NodeTable[fnode->pred[i]];
+ if (Bv_IsBitSet(fnode->index, pred->dom)) {
+ if (!x) {
+ Bv_AllocVector(&InLoop, IRO_NumNodes + 1);
+ Bv_Clear(InLoop);
+ Bv_SetBit(fnode->index, InLoop);
+ }
+ x = 1;
+ Bv_SetBit(pred->index, InLoop);
+ if (pred != fnode)
+ AddPreds(pred);
+ }
+ }
+
+ if (x) {
+ IRO_Dump("IRO_FindEmptyLoops:Found loop with header %d\n", fnode->index);
+ IRO_DumpBits("Loop includes: ", InLoop);
+ EmptyLoop(fnode);
+ IRO_UpdateFlagsOnInts();
+ }
+ }
+
+ IRO_CheckForUserBreak();
+}
+
+static Boolean EmptyLoop(IRONode *fnode) {
+ VarRecord *var;
+ IRONode *bestpred;
+ IRONode *pred;
+ UInt16 i;
+ int flag2;
+ IRONode *r24;
+ Boolean flag;
+ int counter;
+ int j;
+ IRONode *succ;
+ IRONode *bestsucc;
+ int counter2;
+ UInt32 counter3;
+ IROLoop *loop;
+ IRONode *r21;
+ IRONode *r20;
+ IROLinear *constnd;
+ Type *type20;
+ ENode *enode;
+ IROLinear *save;
+
+ flag = 0;
+ counter = 0;
+ LoopNode = fnode;
+ FindMustReach();
+
+ for (var = IRO_FirstVar; var; var = var->next)
+ var->xA = 1;
+
+ ComputeLoopKills();
+ ComputeLoopInvariance();
+ ComputeLoopInduction();
+
+ LoopNode = fnode;
+ ConditionalHeaderAtBottom = 0;
+
+ bestpred = NULL;
+ flag2 = 0;
+ for (i = 0; i < LoopNode->numpred; i++) {
+ pred = IRO_NodeTable[LoopNode->pred[i]];
+ if (!Bv_IsBitSet(pred->index, InLoop)) {
+ flag2 = 1;
+ if (pred->nextnode == fnode) {
+ CError_ASSERT(173, !bestpred || pred == bestpred);
+ bestpred = pred;
+ }
+ }
+ }
+
+ if (!flag2) {
+ IRO_Dump("No predecessor outside the loop\n");
+ return 0;
+ }
+
+ bestsucc = NULL;
+ for (i = 0; i < LoopNode->numsucc; i++) {
+ succ = IRO_NodeTable[LoopNode->succ[i]];
+ if (Bv_IsBitSet(succ->index, InLoop)) {
+ bestsucc = succ;
+ counter++;
+ }
+ }
+
+ if (LoopNode == bestsucc && counter == 1)
+ flag = 1;
+
+ if (LoopNode->last->type != IROLinearIf || LoopNode->last->type != IROLinearIfNot || flag) {
+ counter2 = 0;
+ for (j = 0; j < LoopNode->numpred; j++) {
+ if (Bv_IsBitSet(IRO_NodeTable[LoopNode->pred[j]]->index, InLoop)) {
+ r21 = IRO_NodeTable[LoopNode->pred[j]];
+ counter2++;
+ }
+ }
+
+ r24 = NULL;
+ counter3 = 0;
+ for (j = 0; j < LoopNode->numpred; j++) {
+ if (!Bv_IsBitSet(IRO_NodeTable[LoopNode->pred[j]]->index, InLoop)) {
+ r24 = IRO_NodeTable[LoopNode->pred[j]];
+ counter3++;
+ }
+ }
+
+ if (counter2 == 1 && counter3 == 1) {
+ if (r21->last->type == IROLinearIf) {
+ if ((Bv_IsBitSet(LoopNode->nextnode->index, InLoop) && !Bv_IsBitSet(r21->nextnode->index, InLoop)) || flag) {
+ IRO_Dump("Standard while loop layout\n");
+ loop = ExtractLoopInfo(r21);
+ if (flag)
+ loop->flags |= LoopFlags_20000;
+ FindAssignmenttoInductionVar(loop, r24);
+ r20 = r24;
+ while (r20 && !loop->nd14 && r20->numpred == 1 && IRO_NodeTable[r20->pred[0]]->numsucc == 1) {
+ FindAssignmenttoInductionVar(loop, IRO_NodeTable[r20->pred[0]]);
+ r20 = IRO_NodeTable[r20->pred[0]];
+ }
+
+ if (CanRemoveRedundantLoop(loop)) {
+ IRO_Dump("EmptyLoop: # of iterations =%" PRId32 ", FinalStoreVal=%" PRId32 "\n", CInt64_GetULong(&loop->x28), CInt64_GetULong(&loop->x30));
+ IRO_NopOut(r21->last->u.label.x4);
+ r21->last->type = IROLinearNop;
+ type20 = loop->induction->nd->rtype;
+ constnd = IRO_NewLinear(IROLinearOperand);
+ constnd->index = ++IRO_NumLinear;
+ enode = IRO_NewENode(EINTCONST);
+ enode->rtype = type20;
+ enode->data.intval = loop->x30;
+ constnd->u.node = enode;
+ constnd->rtype = type20;
+
+ if (loop->induction->nd->type == IROLinearOp1Arg) {
+ save = loop->induction->nd->u.monadic;
+ loop->induction->nd->type = IROLinearOp2Arg;
+ loop->induction->nd->nodetype = EASS;
+ loop->induction->nd->u.diadic.left = save;
+ loop->induction->nd->u.diadic.right = constnd;
+ IRO_Paste(constnd, constnd, loop->induction->nd);
+ } else if (loop->induction->nd->type == IROLinearOp2Arg) {
+ loop->induction->nd->nodetype = EASS;
+ IRO_NopOut(loop->induction->nd->u.diadic.right);
+ loop->induction->nd->u.diadic.right = constnd;
+ IRO_Paste(constnd, constnd, loop->induction->nd);
+ }
+ } else if (CanRemoveRedundantLoop1(loop)) {
+ IRO_Dump("EmptyLoop: self recursive dowhile(--n ) loop\n");
+
+ r21->last->type = IROLinearNop;
+ type20 = loop->induction->nd->rtype;
+ constnd = IRO_NewLinear(IROLinearOperand);
+ constnd->index = ++IRO_NumLinear;
+ enode = IRO_NewENode(EINTCONST);
+ enode->rtype = type20;
+ enode->data.intval = cint64_zero;
+ constnd->u.node = enode;
+ constnd->rtype = type20;
+
+ save = loop->induction->nd->u.monadic;
+ loop->induction->nd->type = IROLinearOp2Arg;
+ loop->induction->nd->nodetype = EASS;
+ loop->induction->nd->u.diadic.left = save;
+ loop->induction->nd->u.diadic.right = constnd;
+ IRO_Paste(constnd, constnd, loop->induction->nd);
+ }
+ } else {
+ IRO_Dump("NonStandard while loop layout\n");
+ }
+ } else {
+ IRO_Dump("NonStandard while loop layout\n");
+ }
+ } else {
+ IRO_Dump("Cannot handle Do While Loop with multiple tails\n");
+ }
+ }
+
+ return 0;
+}
+
+static int CanRemoveRedundantLoop(IROLoop *loop) {
+ IROLinear *inner;
+
+ if (loop->flags & LoopFlags_10000) {
+ IRO_Dump("CanRemoveRedundantLoop:No because detection of dowhile(n--) loop not supported\n");
+ return 0;
+ }
+
+ if (loop->flags & LP_LOOP_HAS_ASM) {
+ IRO_Dump("CanRemoveRedundantLoop:No due to LP_LOOP_HAS_ASM \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_IFEXPR_NON_CANONICAL) {
+ IRO_Dump("CanRemoveRedundantLoop:No due to LP_IFEXPR_NON_CANONICAL \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_LOOP_HAS_CALLS) {
+ IRO_Dump("CanRemoveRedundantLoop:No due to LP_LOOP_HAS_CALLS \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_LOOP_HAS_CNTRLFLOW) {
+ IRO_Dump("CanRemoveRedundantLoop:No due to LP_LOOP_HAS_CNTRLFLOW \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_INDUCTION_NOT_FOUND) {
+ IRO_Dump("CanRemoveRedundantLoop:No due to LP_INDUCTION_NOT_FOUND \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_HAS_MULTIPLE_INDUCTIONS) {
+ IRO_Dump("CanRemoveRedundantLoop:No due to LP_HAS_MULTIPLE_INDUCTIONS \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_LOOP_HDR_HAS_SIDEEFFECTS) {
+ IRO_Dump("CanRemoveRedundantLoop:No due to LP_LOOP_HDR_HAS_SIDEEFFECTS \n");
+ return 0;
+ }
+
+ if (!(loop->flags & LoopFlags_200)) {
+ IRO_Dump("CanRemoveRedundantLoop:No because header does not follow induction update \n");
+ return 0;
+ }
+
+ if (!(loop->flags & LoopFlags_10000)) {
+ inner = loop->nd18->u.diadic.right;
+ if (!IRO_IsIntConstant(inner) && !(inner->flags & IROLF_LoopInvariant)) {
+ IRO_Dump("CanRemoveRedundantLoop:No because Loop Upper Bound is Variant in the loop\n");
+ return 0;
+ }
+
+ if (!loop->nd14) {
+ IRO_Dump("CanRemoveRedundantLoop:No because there is no initialization of loop index in PreHeader\n");
+ return 0;
+ }
+
+ if (!IRO_IsVariable(loop->nd14->u.diadic.left)) {
+ IRO_Dump("CanRemoveRedundantLoop:No because initial value of induction stored thru pointer\n");
+ return 0;
+ }
+
+ if (!IRO_IsUnsignedType(loop->nd14->rtype)) {
+ if (IRO_IsIntConstant(loop->nd14->u.diadic.right)) {
+ if (!CInt64_GreaterEqual(loop->nd14->u.diadic.right->u.node->data.intval, cint64_zero)) {
+ IRO_Dump("CanRemoveRedundantLoop:No because initial value of induction is signed but < 0\n");
+ return 0;
+ }
+ } else {
+ IRO_Dump("CanRemoveRedundantLoop:No because initial value of induction is signed and not constant\n");
+ return 0;
+ }
+ }
+
+ if (!(loop->flags & LP_LOOP_STEP_ISPOS) && !(loop->flags & LP_LOOP_STEP_ISNEG)) {
+ IRO_Dump("CanRemoveRedundantLoop:No because LP_LOOP_STEP_ISPOS/LP_LOOP_STEP_ISNEG is not set\n");
+ return 0;
+ }
+
+ if ((loop->flags & LP_LOOP_STEP_ISPOS) && CheckStepOverFlow1_EmptyLoop(loop, &loop->x28, &loop->x30)) {
+ IRO_Dump("CanRemoveRedundantLoop:No because Final Value of indution will overflow\n");
+ return 0;
+ }
+
+ if ((loop->flags & LP_LOOP_STEP_ISNEG) && CheckStepOverFlow2_EmptyLoop(loop, &loop->x28, &loop->x30)) {
+ IRO_Dump("CanRemoveRedundantLoop:No because Final Value of indution will overflow\n");
+ return 0;
+ }
+ }
+
+ return RedundantLoopCheck(loop) != 0;
+}
+
+static int CanRemoveRedundantLoop1(IROLoop *loop) {
+ if ((loop->flags & LoopFlags_10000) && (loop->flags & LoopFlags_20000)) {
+ if (loop->flags & LP_LOOP_HAS_ASM) {
+ IRO_Dump("CanRemoveRedundantLoop1:No due to LP_LOOP_HAS_ASM \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_IFEXPR_NON_CANONICAL) {
+ IRO_Dump("CanRemoveRedundantLoop1:No due to LP_IFEXPR_NON_CANONICAL \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_LOOP_HAS_CALLS) {
+ IRO_Dump("CanRemoveRedundantLoop1:No due to LP_LOOP_HAS_CALLS \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_LOOP_HAS_CNTRLFLOW) {
+ IRO_Dump("CanRemoveRedundantLoop1:No due to LP_LOOP_HAS_CNTRLFLOW \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_INDUCTION_NOT_FOUND) {
+ IRO_Dump("CanRemoveRedundantLoop1:No due to LP_INDUCTION_NOT_FOUND \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_HAS_MULTIPLE_INDUCTIONS) {
+ IRO_Dump("CanRemoveRedundantLoop1:No due to LP_HAS_MULTIPLE_INDUCTIONS \n");
+ return 0;
+ }
+
+ if (loop->flags & LP_LOOP_HDR_HAS_SIDEEFFECTS) {
+ IRO_Dump("CanRemoveRedundantLoop1:No due to LP_LOOP_HDR_HAS_SIDEEFFECTS \n");
+ return 0;
+ }
+
+ if (!(loop->flags & LoopFlags_200)) {
+ IRO_Dump("CanRemoveRedundantLoop1:No because header does not follow induction update \n");
+ return 0;
+ }
+
+ if (loop->induction->nd->type == IROLinearOp1Arg && loop->induction->nd->nodetype == EPREDEC) {
+ if (IRO_IsUnsignedType(loop->induction->nd->rtype))
+ return 1;
+ IRO_Dump("CanRemoveRedundantLoop1:No because induction not of the right type \n");
+ return 0;
+ }
+
+ IRO_Dump("CanRemoveRedundantLoop1:No because induction operator not a predec \n");
+ return 0;
+ } else {
+ return 0;
+ }
+}
+
+static int RedundantLoopCheck(IROLoop *loop) {
+ IRONode *fnode;
+ IROLinear *nd;
+
+ for (fnode = IRO_FirstNode; fnode; fnode = fnode->nextnode) {
+ if (Bv_IsBitSet(fnode->index, InLoop) && fnode != loop->fnode && (nd = fnode->first)) {
+ while (1) {
+ if ((nd->index < loop->index20 || nd->index > loop->index24) && nd->type != IROLinearNop && nd->type != IROLinearLabel) {
+ if (IS_LINEAR_DIADIC(nd, EASS)) {
+ if (!(nd->flags & IROLF_Reffed)) {
+ if (IS_LINEAR_MONADIC(nd->u.diadic.left, EINDIRECT)) {
+ if (nd->u.diadic.left->rtype && CParser_IsVolatile(nd->u.diadic.left->rtype, nd->u.diadic.left->nodeflags & ENODE_FLAG_QUALS)) {
+ IRO_Dump(" EASS at %d fail as store to volatile memory \n", nd->index);
+ return 0;
+ }
+
+ if ((nd->u.diadic.left->u.monadic->flags & IROLF_LoopInvariant) && (nd->u.diadic.right->flags & IROLF_LoopInvariant)) {
+ IRO_Dump(" EASS at %d pass\n", nd->index);
+ } else {
+ IRO_Dump(" EASS at %d fail, either LHS address or RHS is variant \n", nd->index);
+ return 0;
+ }
+ } else {
+ IRO_Dump("Found EASS nodes whose lhs root is not a EINDIRECT node\n");
+ return 0;
+ }
+ } else {
+ IRO_Dump("Found EASS node that is referenced i.e embedded assignment\n");
+ return 0;
+ }
+ } else {
+ if (!(nd->flags & IROLF_Reffed)) {
+ IRO_Dump("Found non EASS top level node in the loop\n");
+ return 0;
+ }
+ }
+ }
+
+ if (nd == fnode->last)
+ break;
+ nd = nd->next;
+ }
+ }
+ }
+
+ return 1;
+}
+
+static int CheckStepOverFlow1_EmptyLoop(IROLoop *loop, CInt64 *val1, CInt64 *val2) {
+ Boolean isUnsigned;
+ IROLinear *nd2;
+ IROLinear *nd1;
+ CInt64 nd2value;
+ CInt64 nd1value;
+ CInt64 addConst;
+ CInt64 work;
+ CInt64 neg1;
+
+ nd2 = loop->nd14->u.diadic.right;
+ nd1 = loop->nd18->u.diadic.right;
+ isUnsigned = IRO_IsUnsignedType(loop->nd18->u.diadic.right->rtype);
+
+ if (IRO_IsIntConstant(nd2) && IRO_IsIntConstant(nd1)) {
+ nd2value = nd2->u.node->data.intval;
+ nd1value = nd1->u.node->data.intval;
+ if (isUnsigned) {
+ if (CInt64_LessEqualU(nd1value, nd2value))
+ return 1;
+ } else {
+ if (CInt64_LessEqual(nd1value, nd2value))
+ return 1;
+ }
+
+ CInt64_SetLong(&addConst, loop->induction->addConst);
+ CInt64_SetLong(&neg1, -1);
+ *val1 = CInt64_Sub(nd1value, nd2value);
+ *val1 = CInt64_Add(*val1, addConst);
+ if (IS_LINEAR_DIADIC(loop->nd18, ELESS))
+ *val1 = CInt64_Add(*val1, neg1);
+
+ CError_ASSERT(855, !CInt64_IsZero(&addConst));
+
+ if (isUnsigned)
+ *val1 = CInt64_DivU(*val1, addConst);
+ else
+ *val1 = CInt64_Div(*val1, addConst);
+
+ if (CInt64_Equal(*val1, cint64_zero))
+ return 1;
+
+ if (isUnsigned) {
+ if (CInt64_LessEqualU(*val1, cint64_zero))
+ CError_FATAL(877);
+ } else {
+ if (CInt64_LessEqual(*val1, cint64_zero))
+ CError_FATAL(886);
+ }
+
+ if (isUnsigned) {
+ *val2 = CInt64_MulU(*val1, addConst);
+ *val2 = CInt64_Add(*val2, nd2value);
+ } else {
+ *val2 = CInt64_Mul(*val1, addConst);
+ *val2 = CInt64_Add(*val2, nd2value);
+ }
+ } else {
+ return 1;
+ }
+
+ CInt64_SetLong(&addConst, loop->induction->addConst);
+ work = CInt64_Add(nd1value, addConst);
+
+ if (isUnsigned) {
+ if (CInt64_LessU(work, nd1value))
+ return 1;
+ } else {
+ if (CInt64_Less(work, nd1value))
+ return 1;
+ }
+
+ return 0;
+}
+
+static int CheckStepOverFlow2_EmptyLoop(IROLoop *loop, CInt64 *val1, CInt64 *val2) {
+ Boolean isUnsigned;
+ IROLinear *nd2;
+ IROLinear *nd1;
+ CInt64 nd2value;
+ CInt64 nd1value;
+ CInt64 addConst;
+ CInt64 work;
+ CInt64 neg1;
+
+ nd1 = loop->nd14->u.diadic.right;
+ nd2 = loop->nd18->u.diadic.right;
+ isUnsigned = IRO_IsUnsignedType(loop->nd18->u.diadic.right->rtype);
+
+ if (IRO_IsIntConstant(nd2) && IRO_IsIntConstant(nd1)) {
+ nd2value = nd2->u.node->data.intval;
+ nd1value = nd1->u.node->data.intval;
+ if (isUnsigned) {
+ if (CInt64_LessEqualU(nd1value, nd2value))
+ return 1;
+ } else {
+ if (CInt64_LessEqual(nd1value, nd2value))
+ return 1;
+ }
+
+ CInt64_SetLong(&addConst, loop->induction->addConst);
+ CInt64_SetLong(&neg1, -1);
+ *val1 = CInt64_Sub(nd1value, nd2value);
+ *val1 = CInt64_Add(*val1, addConst);
+ if (IS_LINEAR_DIADIC(loop->nd18, EGREATER))
+ *val1 = CInt64_Add(*val1, neg1);
+
+ CError_ASSERT(995, !CInt64_IsZero(&addConst));
+
+ if (isUnsigned)
+ *val1 = CInt64_DivU(*val1, addConst);
+ else
+ *val1 = CInt64_Div(*val1, addConst);
+
+ if (CInt64_Equal(*val1, cint64_zero))
+ return 1;
+
+ if (isUnsigned) {
+ if (CInt64_LessEqualU(*val1, cint64_zero))
+ return 0;
+ } else {
+ if (CInt64_LessEqual(*val1, cint64_zero))
+ return 0;
+ }
+
+ if (isUnsigned) {
+ *val2 = CInt64_MulU(*val1, addConst);
+ *val2 = CInt64_Sub(nd1value, *val2);
+ } else {
+ *val2 = CInt64_Mul(*val1, addConst);
+ *val2 = CInt64_Sub(nd1value, *val2);
+ }
+ } else {
+ return 1;
+ }
+
+ CInt64_SetLong(&addConst, loop->induction->addConst);
+ work = CInt64_Sub(nd2value, addConst);
+
+ if (isUnsigned) {
+ if (CInt64_GreaterU(work, nd2value))
+ return 1;
+ } else {
+ if (CInt64_Greater(work, nd1value))
+ return 1;
+ }
+
+ return 0;
+}
+
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