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[EarlyCSE] Add debug counter for debugging mis-optimizations. NFC.
Reviewers: reames, spatel, davide, dberlin Subscribers: mcrosier, llvm-commits Differential Revision: https://reviews.llvm.org/D45162 llvm-svn: 329443
This commit is contained in:
Geoff Berry
parent
398e5f03a7
commit
18fcd57acc
@ -50,6 +50,7 @@
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#include "llvm/Support/AtomicOrdering.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/DebugCounter.h"
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#include "llvm/Support/RecyclingAllocator.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/Scalar.h"
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@ -70,6 +71,9 @@ STATISTIC(NumCSELoad, "Number of load instructions CSE'd");
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STATISTIC(NumCSECall, "Number of call instructions CSE'd");
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STATISTIC(NumDSE, "Number of trivial dead stores removed");
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DEBUG_COUNTER(CSECounter, "early-cse",
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"Controls which instructions are removed");
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//===----------------------------------------------------------------------===//
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// SimpleValue
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//===----------------------------------------------------------------------===//
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@ -727,11 +731,15 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
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DEBUG(dbgs() << "EarlyCSE CVP: Add conditional value for '"
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<< CondInst->getName() << "' as " << *TorF << " in "
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<< BB->getName() << "\n");
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// Replace all dominated uses with the known value.
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if (unsigned Count = replaceDominatedUsesWith(
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CondInst, TorF, DT, BasicBlockEdge(Pred, BB))) {
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Changed = true;
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NumCSECVP += Count;
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if (!DebugCounter::shouldExecute(CSECounter)) {
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DEBUG(dbgs() << "Skipping due to debug counter\n");
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} else {
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// Replace all dominated uses with the known value.
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if (unsigned Count = replaceDominatedUsesWith(
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CondInst, TorF, DT, BasicBlockEdge(Pred, BB))) {
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Changed = true;
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NumCSECVP += Count;
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}
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}
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}
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}
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@ -751,6 +759,10 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
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// Dead instructions should just be removed.
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if (isInstructionTriviallyDead(Inst, &TLI)) {
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DEBUG(dbgs() << "EarlyCSE DCE: " << *Inst << '\n');
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if (!DebugCounter::shouldExecute(CSECounter)) {
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DEBUG(dbgs() << "Skipping due to debug counter\n");
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continue;
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}
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salvageDebugInfo(*Inst);
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removeMSSA(Inst);
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Inst->eraseFromParent();
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@ -840,21 +852,25 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
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// its simpler value.
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if (Value *V = SimplifyInstruction(Inst, SQ)) {
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DEBUG(dbgs() << "EarlyCSE Simplify: " << *Inst << " to: " << *V << '\n');
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bool Killed = false;
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if (!Inst->use_empty()) {
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Inst->replaceAllUsesWith(V);
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Changed = true;
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if (!DebugCounter::shouldExecute(CSECounter)) {
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DEBUG(dbgs() << "Skipping due to debug counter\n");
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} else {
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bool Killed = false;
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if (!Inst->use_empty()) {
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Inst->replaceAllUsesWith(V);
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Changed = true;
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}
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if (isInstructionTriviallyDead(Inst, &TLI)) {
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removeMSSA(Inst);
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Inst->eraseFromParent();
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Changed = true;
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Killed = true;
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}
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if (Changed)
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++NumSimplify;
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if (Killed)
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continue;
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}
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if (isInstructionTriviallyDead(Inst, &TLI)) {
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removeMSSA(Inst);
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Inst->eraseFromParent();
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Changed = true;
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Killed = true;
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}
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if (Changed)
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++NumSimplify;
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if (Killed)
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continue;
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}
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// If this is a simple instruction that we can value number, process it.
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@ -862,6 +878,10 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
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// See if the instruction has an available value. If so, use it.
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if (Value *V = AvailableValues.lookup(Inst)) {
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DEBUG(dbgs() << "EarlyCSE CSE: " << *Inst << " to: " << *V << '\n');
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if (!DebugCounter::shouldExecute(CSECounter)) {
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DEBUG(dbgs() << "Skipping due to debug counter\n");
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continue;
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}
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if (auto *I = dyn_cast<Instruction>(V))
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I->andIRFlags(Inst);
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Inst->replaceAllUsesWith(V);
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@ -919,6 +939,10 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
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if (Op != nullptr) {
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DEBUG(dbgs() << "EarlyCSE CSE LOAD: " << *Inst
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<< " to: " << *InVal.DefInst << '\n');
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if (!DebugCounter::shouldExecute(CSECounter)) {
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DEBUG(dbgs() << "Skipping due to debug counter\n");
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continue;
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}
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if (!Inst->use_empty())
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Inst->replaceAllUsesWith(Op);
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removeMSSA(Inst);
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@ -958,6 +982,10 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
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Inst)) {
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DEBUG(dbgs() << "EarlyCSE CSE CALL: " << *Inst
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<< " to: " << *InVal.first << '\n');
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if (!DebugCounter::shouldExecute(CSECounter)) {
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DEBUG(dbgs() << "Skipping due to debug counter\n");
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continue;
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}
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if (!Inst->use_empty())
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Inst->replaceAllUsesWith(InVal.first);
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removeMSSA(Inst);
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@ -1009,6 +1037,10 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
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MSSA) &&
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"can't have an intervening store if not using MemorySSA!");
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DEBUG(dbgs() << "EarlyCSE DSE (writeback): " << *Inst << '\n');
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if (!DebugCounter::shouldExecute(CSECounter)) {
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DEBUG(dbgs() << "Skipping due to debug counter\n");
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continue;
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}
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removeMSSA(Inst);
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Inst->eraseFromParent();
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Changed = true;
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@ -1041,11 +1073,15 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
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if (LastStoreMemInst.isMatchingMemLoc(MemInst)) {
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DEBUG(dbgs() << "EarlyCSE DEAD STORE: " << *LastStore
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<< " due to: " << *Inst << '\n');
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removeMSSA(LastStore);
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LastStore->eraseFromParent();
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Changed = true;
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++NumDSE;
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LastStore = nullptr;
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if (!DebugCounter::shouldExecute(CSECounter)) {
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DEBUG(dbgs() << "Skipping due to debug counter\n");
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} else {
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removeMSSA(LastStore);
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LastStore->eraseFromParent();
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Changed = true;
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++NumDSE;
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LastStore = nullptr;
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}
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}
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// fallthrough - we can exploit information about this store
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}
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27
test/Other/debugcounter-earlycse.ll
Normal file
27
test/Other/debugcounter-earlycse.ll
Normal file
@ -0,0 +1,27 @@
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; REQUIRES: asserts
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; RUN: opt -S -debug-counter=early-cse-skip=1,early-cse-count=1 -early-cse < %s 2>&1 | FileCheck %s
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;; Test that, with debug counters on, we only optimize the second CSE opportunity.
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define i32 @test(i32 %a, i32 %b) {
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; CHECK-LABEL: @test(
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; CHECK-NEXT: bb:
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; CHECK-NEXT: %add1 = add i32 %a, %b
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; CHECK-NEXT: %add2 = add i32 %a, %b
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; CHECK-NEXT: %add4 = add i32 %a, %b
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; CHECK-NEXT: %ret1 = add i32 %add1, %add2
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; CHECK-NEXT: %ret2 = add i32 %add1, %add4
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; CHECK-NEXT: %ret = add i32 %ret1, %ret2
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; CHECK-NEXT: ret i32 %ret
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;
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bb:
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%add1 = add i32 %a, %b
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%add2 = add i32 %a, %b
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%add3 = add i32 %a, %b
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%add4 = add i32 %a, %b
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%ret1 = add i32 %add1, %add2
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%ret2 = add i32 %add3, %add4
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%ret = add i32 %ret1, %ret2
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ret i32 %ret
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}
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