[llvm] r247184 - ScalarEvolution assume hanging bugfix
Piotr Padlewski via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 9 13:47:30 PDT 2015
Author: prazek
Date: Wed Sep 9 15:47:30 2015
New Revision: 247184
URL: http://llvm.org/viewvc/llvm-project?rev=247184&view=rev
Log:
ScalarEvolution assume hanging bugfix
http://reviews.llvm.org/D12719
Added:
llvm/trunk/test/Analysis/ScalarEvolution/avoid-assume-hang.ll
Modified:
llvm/trunk/lib/Analysis/ScalarEvolution.cpp
Modified: llvm/trunk/lib/Analysis/ScalarEvolution.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolution.cpp?rev=247184&r1=247183&r2=247184&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolution.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolution.cpp Wed Sep 9 15:47:30 2015
@@ -6958,18 +6958,6 @@ ScalarEvolution::isLoopBackedgeGuardedBy
LoopContinuePredicate->getSuccessor(0) != L->getHeader()))
return true;
- // Check conditions due to any @llvm.assume intrinsics.
- for (auto &AssumeVH : AC.assumptions()) {
- if (!AssumeVH)
- continue;
- auto *CI = cast<CallInst>(AssumeVH);
- if (!DT.dominates(CI, Latch->getTerminator()))
- continue;
-
- if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
- return true;
- }
-
struct ClearWalkingBEDominatingCondsOnExit {
ScalarEvolution &SE;
@@ -6981,7 +6969,7 @@ ScalarEvolution::isLoopBackedgeGuardedBy
}
};
- // We don't want more than one activation of the following loop on the stack
+ // We don't want more than one activation of the following loops on the stack
// -- that can lead to O(n!) time complexity.
if (WalkingBEDominatingConds)
return false;
@@ -6989,6 +6977,18 @@ ScalarEvolution::isLoopBackedgeGuardedBy
WalkingBEDominatingConds = true;
ClearWalkingBEDominatingCondsOnExit ClearOnExit(*this);
+ // Check conditions due to any @llvm.assume intrinsics.
+ for (auto &AssumeVH : AC.assumptions()) {
+ if (!AssumeVH)
+ continue;
+ auto *CI = cast<CallInst>(AssumeVH);
+ if (!DT.dominates(CI, Latch->getTerminator()))
+ continue;
+
+ if (isImpliedCond(Pred, LHS, RHS, CI->getArgOperand(0), false))
+ return true;
+ }
+
// If the loop is not reachable from the entry block, we risk running into an
// infinite loop as we walk up into the dom tree. These loops do not matter
// anyway, so we just return a conservative answer when we see them.
Added: llvm/trunk/test/Analysis/ScalarEvolution/avoid-assume-hang.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ScalarEvolution/avoid-assume-hang.ll?rev=247184&view=auto
==============================================================================
--- llvm/trunk/test/Analysis/ScalarEvolution/avoid-assume-hang.ll (added)
+++ llvm/trunk/test/Analysis/ScalarEvolution/avoid-assume-hang.ll Wed Sep 9 15:47:30 2015
@@ -0,0 +1,139 @@
+; RUN: opt %s -always-inline | opt -analyze -scalar-evolution
+; There was optimization bug in ScalarEvolution, that causes too long
+; compute time and stack overflow crash.
+
+declare void @body(i32)
+declare void @llvm.assume(i1)
+
+define available_externally void @assume1(i64 %i.ext, i64 %a) alwaysinline {
+ %cmp0 = icmp ne i64 %i.ext, %a
+ call void @llvm.assume(i1 %cmp0)
+
+ %a1 = add i64 %a, 1
+ %cmp1 = icmp ne i64 %i.ext, %a1
+ call void @llvm.assume(i1 %cmp1)
+
+ %a2 = add i64 %a1, 1
+ %cmp2 = icmp ne i64 %i.ext, %a2
+ call void @llvm.assume(i1 %cmp2)
+
+ %a3 = add i64 %a2, 1
+ %cmp3 = icmp ne i64 %i.ext, %a3
+ call void @llvm.assume(i1 %cmp3)
+
+ %a4 = add i64 %a3, 1
+ %cmp4 = icmp ne i64 %i.ext, %a4
+ call void @llvm.assume(i1 %cmp4)
+
+ ret void
+}
+
+define available_externally void @assume2(i64 %i.ext, i64 %a) alwaysinline {
+ call void @assume1(i64 %i.ext, i64 %a)
+
+ %a1 = add i64 %a, 5
+ %cmp1 = icmp ne i64 %i.ext, %a1
+ call void @assume1(i64 %i.ext, i64 %a1)
+
+ %a2 = add i64 %a1, 5
+ %cmp2 = icmp ne i64 %i.ext, %a2
+ call void @assume1(i64 %i.ext, i64 %a2)
+
+ %a3 = add i64 %a2, 5
+ %cmp3 = icmp ne i64 %i.ext, %a3
+ call void @assume1(i64 %i.ext, i64 %a3)
+
+ %a4 = add i64 %a3, 5
+ %cmp4 = icmp ne i64 %i.ext, %a4
+ call void @assume1(i64 %i.ext, i64 %a4)
+
+ ret void
+}
+
+define available_externally void @assume3(i64 %i.ext, i64 %a) alwaysinline {
+ call void @assume2(i64 %i.ext, i64 %a)
+
+ %a1 = add i64 %a, 25
+ %cmp1 = icmp ne i64 %i.ext, %a1
+ call void @assume2(i64 %i.ext, i64 %a1)
+
+ %a2 = add i64 %a1, 25
+ %cmp2 = icmp ne i64 %i.ext, %a2
+ call void @assume2(i64 %i.ext, i64 %a2)
+
+ %a3 = add i64 %a2, 25
+ %cmp3 = icmp ne i64 %i.ext, %a3
+ call void @assume2(i64 %i.ext, i64 %a3)
+
+ %a4 = add i64 %a3, 25
+ %cmp4 = icmp ne i64 %i.ext, %a4
+ call void @assume2(i64 %i.ext, i64 %a4)
+
+ ret void
+}
+
+define available_externally void @assume4(i64 %i.ext, i64 %a) alwaysinline {
+ call void @assume3(i64 %i.ext, i64 %a)
+
+ %a1 = add i64 %a, 125
+ %cmp1 = icmp ne i64 %i.ext, %a1
+ call void @assume3(i64 %i.ext, i64 %a1)
+
+ %a2 = add i64 %a1, 125
+ %cmp2 = icmp ne i64 %i.ext, %a2
+ call void @assume3(i64 %i.ext, i64 %a2)
+
+ %a3 = add i64 %a2, 125
+ %cmp3 = icmp ne i64 %i.ext, %a3
+ call void @assume3(i64 %i.ext, i64 %a3)
+
+ %a4 = add i64 %a3, 125
+ %cmp4 = icmp ne i64 %i.ext, %a4
+ call void @assume3(i64 %i.ext, i64 %a4)
+
+ ret void
+}
+
+define available_externally void @assume5(i64 %i.ext, i64 %a) alwaysinline {
+ call void @assume4(i64 %i.ext, i64 %a)
+
+ %a1 = add i64 %a, 625
+ %cmp1 = icmp ne i64 %i.ext, %a1
+ call void @assume4(i64 %i.ext, i64 %a1)
+
+ %a2 = add i64 %a1, 625
+ %cmp2 = icmp ne i64 %i.ext, %a2
+ call void @assume4(i64 %i.ext, i64 %a2)
+
+ %a3 = add i64 %a2, 625
+ %cmp3 = icmp ne i64 %i.ext, %a3
+ call void @assume4(i64 %i.ext, i64 %a3)
+
+ %a4 = add i64 %a3, 625
+ %cmp4 = icmp ne i64 %i.ext, %a4
+ call void @assume4(i64 %i.ext, i64 %a4)
+
+ ret void
+}
+
+define void @fn(i32 %init) {
+entry:
+ br label %loop
+
+loop:
+ %i = phi i32 [%init, %entry], [%next, %loop]
+ call void @body(i32 %i)
+
+ %i.ext = zext i32 %i to i64
+
+ call void @assume5(i64 %i.ext, i64 500000000)
+
+ %i.next = add i64 %i.ext, 1
+ %next = trunc i64 %i.next to i32
+ %done = icmp eq i32 %i, 500000000
+
+ br i1 %done, label %exit, label %loop
+
+exit:
+ ret void
+}
\ No newline at end of file
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