[llvm] r206789 - Fix PR7272 in -tailcallelim instead of the inliner
Reid Kleckner
reid at kleckner.net
Mon Apr 21 13:48:47 PDT 2014
Author: rnk
Date: Mon Apr 21 15:48:47 2014
New Revision: 206789
URL: http://llvm.org/viewvc/llvm-project?rev=206789&view=rev
Log:
Fix PR7272 in -tailcallelim instead of the inliner
The -tailcallelim pass should be checking if byval or inalloca args can
be captured before marking calls as tail calls. This was the real root
cause of PR7272.
With a better fix in place, revert the inliner change from r105255. The
test case it introduced still passes and has been moved to
test/Transforms/Inline/byval-tail-call.ll.
Reviewers: chandlerc
Differential Revision: http://reviews.llvm.org/D3403
Added:
llvm/trunk/test/Transforms/Inline/byval-tail-call.ll
- copied, changed from r206788, llvm/trunk/test/Transforms/Inline/2010-05-31-ByvalTailcall.ll
Removed:
llvm/trunk/test/Transforms/Inline/2010-05-31-ByvalTailcall.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp
llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
llvm/trunk/test/Transforms/TailCallElim/basic.ll
Modified: llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp?rev=206789&r1=206788&r2=206789&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/TailRecursionElimination.cpp Mon Apr 21 15:48:47 2014
@@ -204,6 +204,15 @@ bool TailCallElim::runOnFunction(Functio
}
}
+ // If any byval or inalloca args are captured, exit. They are also allocated
+ // in our stack frame.
+ for (Argument &Arg : F.args()) {
+ if (Arg.hasByValOrInAllocaAttr())
+ PointerMayBeCaptured(&Arg, &ACT);
+ if (ACT.Captured)
+ return false;
+ }
+
// Second pass, change any tail recursive calls to loops.
//
// FIXME: The code generator produces really bad code when an 'escaping
Modified: llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp?rev=206789&r1=206788&r2=206789&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/InlineFunction.cpp Mon Apr 21 15:48:47 2014
@@ -586,15 +586,8 @@ bool llvm::InlineFunction(CallSite CS, I
if (CS.isByValArgument(ArgNo)) {
ActualArg = HandleByValArgument(ActualArg, TheCall, CalledFunc, IFI,
CalledFunc->getParamAlignment(ArgNo+1));
-
- // Calls that we inline may use the new alloca, so we need to clear
- // their 'tail' flags if HandleByValArgument introduced a new alloca and
- // the callee has calls.
- if (ActualArg != *AI) {
- MustClearTailCallFlags = true;
+ if (ActualArg != *AI)
ByValInit.push_back(std::make_pair(ActualArg, (Value*) *AI));
- }
-
}
VMap[I] = ActualArg;
Removed: llvm/trunk/test/Transforms/Inline/2010-05-31-ByvalTailcall.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/2010-05-31-ByvalTailcall.ll?rev=206788&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/Inline/2010-05-31-ByvalTailcall.ll (original)
+++ llvm/trunk/test/Transforms/Inline/2010-05-31-ByvalTailcall.ll (removed)
@@ -1,25 +0,0 @@
-; RUN: opt < %s -tailcallelim -inline -instcombine -dse -S | FileCheck %s
-; PR7272
-
-; When inlining through a byval call site, the inliner creates allocas which may
-; be used by inlined calls, so any inlined calls need to have their 'tail' flags
-; cleared. If not then you can get nastiness like with this testcase, where the
-; (inlined) call to 'ext' in 'foo' was being passed an uninitialized value.
-
-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-f80:32:32-n8:16:32"
-target triple = "i386-pc-linux-gnu"
-
-declare void @ext(i32*)
-
-define void @bar(i32* byval %x) {
- call void @ext(i32* %x)
- ret void
-}
-
-define void @foo(i32* %x) {
-; CHECK-LABEL: define void @foo(
-; CHECK: llvm.lifetime.start
-; CHECK: store i32 %2, i32* %x
- call void @bar(i32* byval %x)
- ret void
-}
Copied: llvm/trunk/test/Transforms/Inline/byval-tail-call.ll (from r206788, llvm/trunk/test/Transforms/Inline/2010-05-31-ByvalTailcall.ll)
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/Inline/byval-tail-call.ll?p2=llvm/trunk/test/Transforms/Inline/byval-tail-call.ll&p1=llvm/trunk/test/Transforms/Inline/2010-05-31-ByvalTailcall.ll&r1=206788&r2=206789&rev=206789&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/Inline/2010-05-31-ByvalTailcall.ll (original)
+++ llvm/trunk/test/Transforms/Inline/byval-tail-call.ll Mon Apr 21 15:48:47 2014
@@ -1,10 +1,8 @@
; RUN: opt < %s -tailcallelim -inline -instcombine -dse -S | FileCheck %s
; PR7272
-; When inlining through a byval call site, the inliner creates allocas which may
-; be used by inlined calls, so any inlined calls need to have their 'tail' flags
-; cleared. If not then you can get nastiness like with this testcase, where the
-; (inlined) call to 'ext' in 'foo' was being passed an uninitialized value.
+; Calls that capture byval parameters cannot be marked as tail calls. Other
+; tails that don't capture byval parameters can still be tail calls.
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-f80:32:32-n8:16:32"
target triple = "i386-pc-linux-gnu"
@@ -23,3 +21,18 @@ define void @foo(i32* %x) {
call void @bar(i32* byval %x)
ret void
}
+
+define internal void @qux(i32* byval %x) {
+ call void @ext(i32* %x)
+ tail call void @ext(i32* null)
+ ret void
+}
+define void @frob(i32* %x) {
+; CHECK-LABEL: define void @frob(
+; CHECK: alloca i32
+; CHECK: {{^ *}}call void @ext(
+; CHECK: tail call void @ext(i32* null)
+; CHECK: ret void
+ tail call void @qux(i32* byval %x)
+ ret void
+}
Modified: llvm/trunk/test/Transforms/TailCallElim/basic.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/TailCallElim/basic.ll?rev=206789&r1=206788&r2=206789&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/TailCallElim/basic.ll (original)
+++ llvm/trunk/test/Transforms/TailCallElim/basic.ll Mon Apr 21 15:48:47 2014
@@ -143,3 +143,11 @@ cond_false:
call void @noarg()
ret i32* null
}
+
+; Don't tail call if a byval arg is captured.
+define void @test9(i32* byval %a) {
+; CHECK-LABEL: define void @test9(
+; CHECK: {{^ *}}call void @use(
+ call void @use(i32* %a)
+ ret void
+}
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