[llvm] r352469 - [IPCP] Don't crash due to arg count/type mismatch between caller/callee
Bjorn Pettersson via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 29 02:19:45 PST 2019
Author: bjope
Date: Tue Jan 29 02:19:44 2019
New Revision: 352469
URL: http://llvm.org/viewvc/llvm-project?rev=352469&view=rev
Log:
[IPCP] Don't crash due to arg count/type mismatch between caller/callee
Summary:
This patch avoids an assert in IPConstantPropagation when
there is a argument count/type mismatch between the caller and
the callee.
While this is actually UB on C-level (clang emits a warning),
the IR verifier seems to accept it. I'm not sure what other
frontends/languages might think about this, so simply bailing out
to avoid hitting an assert (in CallSiteBase<>::getArgOperand or
Value::doRAUW) seems like a simple solution.
The problem is exposed by the fact that AbstractCallSites will look
through a bitcast at the callee position of a call/invoke.
Reviewers: jdoerfert, reames, efriedma
Reviewed By: jdoerfert, efriedma
Subscribers: eli.friedman, efriedma, llvm-commits
Differential Revision: https://reviews.llvm.org/D57052
Added:
llvm/trunk/test/Transforms/IPConstantProp/arg-count-mismatch.ll
llvm/trunk/test/Transforms/IPConstantProp/arg-type-mismatch.ll
Modified:
llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp
Modified: llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp?rev=352469&r1=352468&r2=352469&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/IPConstantPropagation.cpp Tue Jan 29 02:19:44 2019
@@ -66,6 +66,13 @@ static bool PropagateConstantsIntoArgume
if (!ACS)
return false;
+ // Mismatched argument count is undefined behavior. Simply bail out to avoid
+ // handling of such situations below (avoiding asserts/crashes).
+ unsigned NumActualArgs = ACS.getNumArgOperands();
+ if (F.isVarArg() ? ArgumentConstants.size() > NumActualArgs
+ : ArgumentConstants.size() != NumActualArgs)
+ return false;
+
// Check out all of the potentially constant arguments. Note that we don't
// inspect varargs here.
Function::arg_iterator Arg = F.arg_begin();
@@ -78,6 +85,11 @@ static bool PropagateConstantsIntoArgume
Value *V = ACS.getCallArgOperand(i);
Constant *C = dyn_cast_or_null<Constant>(V);
+ // Mismatched argument type is undefined behavior. Simply bail out to avoid
+ // handling of such situations below (avoiding asserts/crashes).
+ if (C && Arg->getType() != C->getType())
+ return false;
+
// We can only propagate thread independent values through callbacks.
// This is different to direct/indirect call sites because for them we
// know the thread executing the caller and callee is the same. For
Added: llvm/trunk/test/Transforms/IPConstantProp/arg-count-mismatch.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IPConstantProp/arg-count-mismatch.ll?rev=352469&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/IPConstantProp/arg-count-mismatch.ll (added)
+++ llvm/trunk/test/Transforms/IPConstantProp/arg-count-mismatch.ll Tue Jan 29 02:19:44 2019
@@ -0,0 +1,72 @@
+; RUN: opt < %s -ipconstprop -S -o - | FileCheck %s
+
+; The original C source looked like this:
+;
+; long long a101, b101, e101;
+; volatile long c101;
+; int d101;
+;
+; static inline int bar(p1, p2)
+; {
+; return 0;
+; }
+;
+; void foo(unsigned p1)
+; {
+; long long *f = &b101, *g = &e101;
+; c101 = 0;
+; (void)((*f |= a101) - (*g = bar(d101)));
+; c101 = (*f |= a101 &= p1) == d101;
+; }
+;
+; When compiled with Clang it gives a warning
+; warning: too few arguments in call to 'bar'
+;
+; This ll reproducer has been reduced to only include tha call.
+;
+; Note that -lint will report this as UB, but it passes -verify.
+
+; This test is just to verify that we do not crash/assert due to mismatch in
+; argument count between the caller and callee.
+
+define dso_local void @foo(i16 %a) {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT: [[CALL:%.*]] = call i16 bitcast (i16 (i16, i16)* @bar to i16 (i16)*)(i16 [[A:%.*]])
+; CHECK-NEXT: ret void
+;
+ %call = call i16 bitcast (i16 (i16, i16) * @bar to i16 (i16) *)(i16 %a)
+ ret void
+}
+
+define internal i16 @bar(i16 %p1, i16 %p2) {
+; CHECK-LABEL: @bar(
+; CHECK-NEXT: ret i16 0
+;
+ ret i16 0
+}
+
+;-------------------------------------------------------------------------------
+; Additional tests to verify that we still optimize when having a mismatch
+; in argument count due to varargs (as long as all non-variadic arguments have
+; been provided),
+
+define dso_local void @vararg_tests(i16 %a) {
+ %call1 = call i16 (i16, ...) @vararg_prop(i16 7, i16 8, i16 %a)
+ %call2 = call i16 bitcast (i16 (i16, i16, ...) * @vararg_no_prop to i16 (i16) *) (i16 7)
+ ret void
+}
+
+define internal i16 @vararg_prop(i16 %p1, ...) {
+; CHECK-LABEL: define internal i16 @vararg_prop(
+; CHECK-NEXT: ret i16 7
+;
+ ret i16 %p1
+}
+
+define internal i16 @vararg_no_prop(i16 %p1, i16 %p2, ...) {
+; CHECK-LABEL: define internal i16 @vararg_no_prop(
+; CHECK-NEXT: ret i16 [[P1:%.*]]
+;
+ ret i16 %p1
+}
+
Added: llvm/trunk/test/Transforms/IPConstantProp/arg-type-mismatch.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IPConstantProp/arg-type-mismatch.ll?rev=352469&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/IPConstantProp/arg-type-mismatch.ll (added)
+++ llvm/trunk/test/Transforms/IPConstantProp/arg-type-mismatch.ll Tue Jan 29 02:19:44 2019
@@ -0,0 +1,23 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -ipconstprop -S -o - | FileCheck %s
+
+; This test is just to verify that we do not crash/assert due to mismatch in
+; argument type between the caller and callee.
+
+define dso_local void @foo(i16 %a) {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT: [[CALL:%.*]] = call i16 bitcast (i16 (i16, i16)* @bar to i16 (i16, i32)*)(i16 [[A:%.*]], i32 7)
+; CHECK-NEXT: ret void
+;
+ %call = call i16 bitcast (i16 (i16, i16) * @bar to i16 (i16, i32) *)(i16 %a, i32 7)
+ ret void
+}
+
+define internal i16 @bar(i16 %p1, i16 %p2) {
+; CHECK-LABEL: @bar(
+; CHECK-NEXT: ret i16 [[P2:%.*]]
+;
+ ret i16 %p2
+}
+
+
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