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[SimplifyCFG] Stop hoisting musttail calls incorrectly.

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PR35774.

llvm-svn: 321603
This commit is contained in:
Davide Italiano 2017-12-31 16:47:16 +00:00
parent 98a2e44b5b
commit 9c4d5be906
2 changed files with 46 additions and 0 deletions
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11
lib/Transforms/Utils/SimplifyCFG.cpp
View File

@ -1276,6 +1276,17 @@ static bool HoistThenElseCodeToIf(BranchInst *BI,
if (isa<TerminatorInst>(I1))
goto HoistTerminator;
// If we're going to hoist a call, make sure that the two instructions we're
// commoning/hoisting are both marked with musttail, or neither of them is
// marked as such. Otherwise, we might end up in a situation where we hoist
// from a block where the terminator is a `ret` to a block where the terminator
// is a `br`, and `musttail` calls expect to be followed by a return.
auto *C1 = dyn_cast<CallInst>(I1);
auto *C2 = dyn_cast<CallInst>(I2);
if (C1 && C2)
if (C1->isMustTailCall() != C2->isMustTailCall())
return false;
if (!TTI.isProfitableToHoist(I1) || !TTI.isProfitableToHoist(I2))
return Changed;

35
test/Transforms/SimplifyCFG/pr35774.ll Normal file
View File

@ -0,0 +1,35 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -simplifycfg -S %s | FileCheck %s
%foo = type { i32 (%foo)*, i32 }
declare i32 @putchar(i32)
define i32 @intercept(%foo %f) {
; CHECK-LABEL: @intercept(
; CHECK-NEXT: [[FN:%.*]] = extractvalue [[FOO:%.*]] %f, 0
; CHECK-NEXT: [[X:%.*]] = extractvalue [[FOO]] %f, 1
; CHECK-NEXT: [[X0:%.*]] = icmp eq i32 [[X]], 0
; CHECK-NEXT: br i1 [[X0]], label [[ZERO:%.*]], label [[NONZERO:%.*]]
; CHECK: Zero:
; CHECK-NEXT: [[R0:%.*]] = musttail call i32 [[FN]](%foo [[F:%.*]])
; CHECK-NEXT: ret i32 [[R0]]
; CHECK: Nonzero:
; CHECK-NEXT: [[R1:%.*]] = tail call i32 [[FN]](%foo [[F]])
; CHECK-NEXT: [[TMP1:%.*]] = tail call i32 @putchar(i32 [[R1]])
; CHECK-NEXT: ret i32 [[R1]]
;
%fn = extractvalue %foo %f, 0
%x = extractvalue %foo %f, 1
%x0 = icmp eq i32 %x, 0
br i1 %x0, label %Zero, label %Nonzero
Zero:
%r0 = musttail call i32 %fn(%foo %f)
ret i32 %r0
Nonzero:
%r1 = tail call i32 %fn(%foo %f)
%1 = tail call i32 @putchar(i32 %r1)
ret i32 %r1
}