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Don't infininitely thread branches when a threaded edge
goes back to the block, e.g.: Threading edge through bool from 'bb37.us.thread3829' to 'bb37.us' with cost: 1, across block: bb37.us: ; preds = %bb37.us.thread3829, %bb37.us, %bb33 %D1361.1.us = phi i32 [ %tmp36, %bb33 ], [ %D1361.1.us, %bb37.us ], [ 0, %bb37.us.thread3829 ] ; <i32> [#uses=2] %tmp39.us = icmp eq i32 %D1361.1.us, 0 ; <i1> [#uses=1] br i1 %tmp39.us, label %bb37.us, label %bb42.us git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50251 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
parent
877ee973e2
commit
eede65ce6c
@ -250,6 +250,13 @@ bool JumpThreading::ProcessJumpOnPHI(PHINode *PN) {
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SuccBB = SI->getSuccessor(SI->findCaseValue(PredCst));
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}
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// If threading to the same block as we come from, we would infinite loop.
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if (SuccBB == BB) {
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DOUT << " Not threading BB '" << BB->getNameStart()
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<< "' - would thread to self!\n";
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return false;
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}
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// And finally, do it!
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DOUT << " Threading edge from '" << PredBB->getNameStart() << "' to '"
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<< SuccBB->getNameStart() << "' with cost: " << JumpThreadCost
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@ -319,6 +326,13 @@ bool JumpThreading::ProcessBranchOnLogical(Value *V, BasicBlock *BB,
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// 'true' block.
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BasicBlock *SuccBB = BB->getTerminator()->getSuccessor(isAnd);
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// If threading to the same block as we come from, we would infinite loop.
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if (SuccBB == BB) {
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DOUT << " Not threading BB '" << BB->getNameStart()
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<< "' - would thread to self!\n";
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return false;
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}
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// And finally, do it!
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DOUT << " Threading edge through bool from '" << PredBB->getNameStart()
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<< "' to '" << SuccBB->getNameStart() << "' with cost: "
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@ -390,6 +404,14 @@ bool JumpThreading::ProcessBranchOnCompare(CmpInst *Cmp, BasicBlock *BB) {
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// Next, get our successor.
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BasicBlock *SuccBB = BB->getTerminator()->getSuccessor(!TrueDirection);
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// If threading to the same block as we come from, we would infinite loop.
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if (SuccBB == BB) {
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DOUT << " Not threading BB '" << BB->getNameStart()
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<< "' - would thread to self!\n";
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return false;
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}
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// And finally, do it!
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DOUT << " Threading edge through bool from '" << PredBB->getNameStart()
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<< "' to '" << SuccBB->getNameStart() << "' with cost: "
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142
test/Transforms/JumpThreading/2008-04-24-InfLoop.ll
Normal file
142
test/Transforms/JumpThreading/2008-04-24-InfLoop.ll
Normal file
@ -0,0 +1,142 @@
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; RUN: llvm-as < %s | opt -jump-threading -disable-output
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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-f80:128:128"
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target triple = "i386-apple-darwin9"
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@Link = global [1 x i32] [ i32 -1 ] ; <[1 x i32]*> [#uses=2]
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@W = global [1 x i32] [ i32 2 ] ; <[1 x i32]*> [#uses=1]
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define i32 @f(i32 %k, i32 %p) nounwind {
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entry:
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br label %bb
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bb: ; preds = %bb56, %bb76.loopexit.us, %entry
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%j.2 = phi i32 [ 0, %entry ], [ 1, %bb56 ], [ 1, %bb76.loopexit.us ] ; <i32> [#uses=5]
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%pdest.2 = phi i32 [ 0, %entry ], [ %pdest.8, %bb56 ], [ %pdest.7.us, %bb76.loopexit.us ] ; <i32> [#uses=3]
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%p_addr.0 = phi i32 [ %p, %entry ], [ 0, %bb56 ], [ %p_addr.1.us, %bb76.loopexit.us ] ; <i32> [#uses=3]
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%k_addr.0 = phi i32 [ %k, %entry ], [ %tmp59, %bb56 ], [ %tmp59.us, %bb76.loopexit.us ] ; <i32> [#uses=4]
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%tmp2 = icmp sgt i32 %pdest.2, 2 ; <i1> [#uses=1]
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br i1 %tmp2, label %bb4.preheader, label %bb13
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bb4.preheader: ; preds = %bb
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%tmp109 = sub i32 1, %j.2 ; <i32> [#uses=2]
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%tmp110 = icmp slt i32 %tmp109, -2 ; <i1> [#uses=1]
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%smax111 = select i1 %tmp110, i32 -2, i32 %tmp109 ; <i32> [#uses=2]
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%tmp112 = add i32 %j.2, %smax111 ; <i32> [#uses=2]
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br label %bb4
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bb4: ; preds = %bb4, %bb4.preheader
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%indvar = phi i32 [ 0, %bb4.preheader ], [ %indvar.next, %bb4 ] ; <i32> [#uses=1]
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%indvar.next = add i32 %indvar, 1 ; <i32> [#uses=2]
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%exitcond = icmp eq i32 %indvar.next, %tmp112 ; <i1> [#uses=1]
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br i1 %exitcond, label %bb13.loopexit, label %bb4
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bb13.loopexit: ; preds = %bb4
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%tmp = add i32 %j.2, %pdest.2 ; <i32> [#uses=1]
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%tmp102 = add i32 %tmp, %smax111 ; <i32> [#uses=1]
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%tmp104 = add i32 %tmp112, -1 ; <i32> [#uses=1]
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%tmp106 = sub i32 %j.2, %tmp104 ; <i32> [#uses=1]
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%tmp107 = add i32 %tmp106, -1 ; <i32> [#uses=1]
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br label %bb13
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bb13: ; preds = %bb13.loopexit, %bb
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%j.1 = phi i32 [ %tmp107, %bb13.loopexit ], [ %j.2, %bb ] ; <i32> [#uses=4]
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%pdest.1 = phi i32 [ %tmp102, %bb13.loopexit ], [ %pdest.2, %bb ] ; <i32> [#uses=2]
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%tmp15 = icmp eq i32 %j.1, 1 ; <i1> [#uses=1]
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br i1 %tmp15, label %bb82, label %bb27.preheader
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bb27.preheader: ; preds = %bb13
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%tmp21 = icmp eq i32 %j.1, %p_addr.0 ; <i1> [#uses=0]
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br label %bb27.outer
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bb27.outer: ; preds = %bb27.outer.bb24.split_crit_edge, %bb27.preheader
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%indvar118 = phi i32 [ 0, %bb27.preheader ], [ %indvar.next119, %bb27.outer.bb24.split_crit_edge ] ; <i32> [#uses=2]
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%pdest.3.ph = add i32 %indvar118, %pdest.1 ; <i32> [#uses=2]
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%tmp30 = icmp sgt i32 %pdest.3.ph, %p_addr.0 ; <i1> [#uses=1]
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br i1 %tmp30, label %bb27.outer.bb24.split_crit_edge, label %bb27.outer.split
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bb27.outer.bb24.split_crit_edge: ; preds = %bb27.outer
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%indvar.next119 = add i32 %indvar118, 1 ; <i32> [#uses=1]
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br label %bb27.outer
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bb27.outer.split: ; preds = %bb27.outer
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%tmp35 = getelementptr [1 x i32]* @W, i32 0, i32 %k_addr.0 ; <i32*> [#uses=3]
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%tmp48 = icmp slt i32 %p_addr.0, 1 ; <i1> [#uses=1]
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%tmp53 = icmp sgt i32 %k_addr.0, 0 ; <i1> [#uses=1]
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br label %bb33
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bb33: ; preds = %bb51.split, %bb27.outer.split
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%pdest.5 = phi i32 [ %pdest.3.ph, %bb27.outer.split ], [ %pdest.4, %bb51.split ] ; <i32> [#uses=1]
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%tmp36 = load i32* %tmp35, align 4 ; <i32> [#uses=2]
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br i1 %tmp48, label %bb37.us, label %bb37
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bb37.us: ; preds = %bb42.us, %bb37.us, %bb33
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%D1361.1.us = phi i32 [ %tmp36, %bb33 ], [ 0, %bb42.us ], [ %D1361.1.us, %bb37.us ] ; <i32> [#uses=2]
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%tmp39.us = icmp eq i32 %D1361.1.us, 0 ; <i1> [#uses=1]
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br i1 %tmp39.us, label %bb37.us, label %bb42.us
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bb42.us: ; preds = %bb37.us
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store i32 0, i32* %tmp35, align 4
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br label %bb37.us
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bb37: ; preds = %bb33
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%tmp39 = icmp eq i32 %tmp36, 0 ; <i1> [#uses=1]
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br i1 %tmp39, label %bb51.split, label %bb42
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bb42: ; preds = %bb37
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store i32 0, i32* %tmp35, align 4
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br label %bb51.split
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bb51.split: ; preds = %bb42, %bb37
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%pdest.4 = phi i32 [ 1, %bb42 ], [ %pdest.5, %bb37 ] ; <i32> [#uses=3]
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br i1 %tmp53, label %bb33, label %bb56.preheader
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bb56.preheader: ; preds = %bb51.split
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%tmp7394 = icmp sgt i32 %j.1, 0 ; <i1> [#uses=1]
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br i1 %tmp7394, label %bb56.us, label %bb56
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bb56.us: ; preds = %bb76.loopexit.us, %bb56.preheader
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%pdest.8.us = phi i32 [ %pdest.4, %bb56.preheader ], [ %pdest.7.us, %bb76.loopexit.us ] ; <i32> [#uses=1]
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%k_addr.1.us = phi i32 [ %k_addr.0, %bb56.preheader ], [ %tmp59.us, %bb76.loopexit.us ] ; <i32> [#uses=1]
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%tmp58.us = getelementptr [1 x i32]* @Link, i32 0, i32 %k_addr.1.us ; <i32*> [#uses=1]
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%tmp59.us = load i32* %tmp58.us, align 4 ; <i32> [#uses=3]
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%tmp6295.us = icmp ne i32 %tmp59.us, -1 ; <i1> [#uses=2]
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br label %bb60.us
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bb60.us: ; preds = %bb60.us, %bb56.us
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%pdest.7.reg2mem.0.us = phi i32 [ %pdest.8.us, %bb56.us ], [ %pdest.7.us, %bb60.us ] ; <i32> [#uses=1]
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%p_addr.1.reg2mem.0.us = phi i32 [ 0, %bb56.us ], [ %p_addr.1.us, %bb60.us ] ; <i32> [#uses=1]
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%tmp67.us = zext i1 %tmp6295.us to i32 ; <i32> [#uses=2]
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%pdest.7.us = add i32 %pdest.7.reg2mem.0.us, %tmp67.us ; <i32> [#uses=3]
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%p_addr.1.us = add i32 %p_addr.1.reg2mem.0.us, %tmp67.us ; <i32> [#uses=3]
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%tmp73.us = icmp slt i32 %p_addr.1.us, %j.1 ; <i1> [#uses=1]
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br i1 %tmp73.us, label %bb60.us, label %bb76.loopexit.us
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bb76.loopexit.us: ; preds = %bb60.us
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br i1 %tmp6295.us, label %bb56.us, label %bb
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bb56: ; preds = %bb56, %bb56.preheader
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%pdest.8 = phi i32 [ %pdest.4, %bb56.preheader ], [ %pdest.8, %bb56 ] ; <i32> [#uses=2]
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%k_addr.1 = phi i32 [ %k_addr.0, %bb56.preheader ], [ %tmp59, %bb56 ] ; <i32> [#uses=1]
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%tmp58 = getelementptr [1 x i32]* @Link, i32 0, i32 %k_addr.1 ; <i32*> [#uses=1]
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%tmp59 = load i32* %tmp58, align 4 ; <i32> [#uses=3]
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%tmp6295 = icmp ne i32 %tmp59, -1 ; <i1> [#uses=1]
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br i1 %tmp6295, label %bb56, label %bb
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bb82: ; preds = %bb13
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ret i32 %pdest.1
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}
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define i32 @main() nounwind {
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entry:
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%tmp1 = tail call i32 @f( i32 0, i32 2 ) nounwind ; <i32> [#uses=1]
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%tmp2 = icmp eq i32 %tmp1, 0 ; <i1> [#uses=1]
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br i1 %tmp2, label %bb, label %bb4
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bb: ; preds = %entry
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tail call void @abort( ) noreturn nounwind
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unreachable
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bb4: ; preds = %entry
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ret i32 0
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}
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declare void @abort() noreturn nounwind
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