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[SimplifyCFG] Fix prof branch_weights MD while removing unreachable switch cases

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SimplifyCFG has a bug that results in inconsistent prof branch_weights metadata
if unreachable switch cases are removed. This patch fixes this bug by making use
of the newly introduced SwitchInstProfUpdateWrapper class (see patch D62122).
A new test is created.

Differential Revision: https://reviews.llvm.org/D62186

llvm-svn: 363527
This commit is contained in:
Yevgeny Rouban 2019-06-17 05:55:12 +00:00
parent 2bad53a983
commit 0b9f7752c8
2 changed files with 40 additions and 4 deletions
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9
lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -4218,14 +4218,15 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
}
}
} else if (auto *SI = dyn_cast<SwitchInst>(TI)) {
for (auto i = SI->case_begin(), e = SI->case_end(); i != e;) {
SwitchInstProfUpdateWrapper SU(*SI);
for (auto i = SU->case_begin(), e = SU->case_end(); i != e;) {
if (i->getCaseSuccessor() != BB) {
++i;
continue;
}
BB->removePredecessor(SI->getParent());
i = SI->removeCase(i);
e = SI->case_end();
BB->removePredecessor(SU->getParent());
i = SU.removeCase(i);
e = SU->case_end();
Changed = true;
}
} else if (auto *II = dyn_cast<InvokeInst>(TI)) {

35
test/Transforms/SimplifyCFG/switch-profmd.ll Normal file
View File

@ -0,0 +1,35 @@
; RUN: opt -S -simplifycfg < %s | FileCheck %s
declare i32 @f(i32 %val)
; Check that eliminating cases with unreachable branches keeps
; prof branch_weights metadata consistent with switch instruction.
define i32 @test_switch_to_unreachable(i32 %val) {
; CHECK-LABEL: test_switch_to_unreachable
; CHECK: switch
; CHECK-NOT: i32 0, label %on0
switch i32 %val, label %otherwise [
i32 0, label %on0
i32 1, label %on1
i32 2, label %on2
], !prof !{!"branch_weights", i32 99, i32 0, i32 1, i32 2}
; CHECK: !prof ![[MD0:[0-9]+]]
otherwise:
%result = call i32 @f(i32 -1)
ret i32 %result
on0:
unreachable
ret i32 125
on1:
%result1 = call i32 @f(i32 -2)
ret i32 %result1
on2:
%result2 = call i32 @f(i32 -3)
ret i32 %result2
}
; CHECK: ![[MD0]] = !{!"branch_weights", i32 99, i32 2, i32 1}