r176056 - [ubsan] Emit single check for left shift.
Will Dietz
wdietz2 at illinois.edu
Mon Feb 25 14:37:49 PST 2013
Author: wdietz2
Date: Mon Feb 25 16:37:49 2013
New Revision: 176056
URL: http://llvm.org/viewvc/llvm-project?rev=176056&view=rev
Log:
[ubsan] Emit single check for left shift.
Avoids warning twice on same shift.
Modified:
cfe/trunk/lib/CodeGen/CGExprScalar.cpp
cfe/trunk/test/CodeGen/catch-undef-behavior.c
cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp
Modified: cfe/trunk/lib/CodeGen/CGExprScalar.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprScalar.cpp?rev=176056&r1=176055&r2=176056&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprScalar.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprScalar.cpp Mon Feb 25 16:37:49 2013
@@ -2407,13 +2407,17 @@ Value *ScalarExprEmitter::EmitShl(const
if (CGF.SanOpts->Shift && !CGF.getLangOpts().OpenCL &&
isa<llvm::IntegerType>(Ops.LHS->getType())) {
llvm::Value *WidthMinusOne = GetWidthMinusOneValue(Ops.LHS, RHS);
- // FIXME: Emit the branching explicitly rather than emitting the check
- // twice.
- EmitBinOpCheck(Builder.CreateICmpULE(RHS, WidthMinusOne), Ops);
+ llvm::Value *Valid = Builder.CreateICmpULE(RHS, WidthMinusOne);
if (Ops.Ty->hasSignedIntegerRepresentation()) {
+ llvm::BasicBlock *Orig = Builder.GetInsertBlock();
+ llvm::BasicBlock *Cont = CGF.createBasicBlock("cont");
+ llvm::BasicBlock *CheckBitsShifted = CGF.createBasicBlock("check");
+ Builder.CreateCondBr(Valid, CheckBitsShifted, Cont);
+
// Check whether we are shifting any non-zero bits off the top of the
// integer.
+ CGF.EmitBlock(CheckBitsShifted);
llvm::Value *BitsShiftedOff =
Builder.CreateLShr(Ops.LHS,
Builder.CreateSub(WidthMinusOne, RHS, "shl.zeros",
@@ -2428,8 +2432,15 @@ Value *ScalarExprEmitter::EmitShl(const
BitsShiftedOff = Builder.CreateLShr(BitsShiftedOff, One);
}
llvm::Value *Zero = llvm::ConstantInt::get(BitsShiftedOff->getType(), 0);
- EmitBinOpCheck(Builder.CreateICmpEQ(BitsShiftedOff, Zero), Ops);
+ llvm::Value *SecondCheck = Builder.CreateICmpEQ(BitsShiftedOff, Zero);
+ CGF.EmitBlock(Cont);
+ llvm::PHINode *P = Builder.CreatePHI(Valid->getType(), 2);
+ P->addIncoming(Valid, Orig);
+ P->addIncoming(SecondCheck, CheckBitsShifted);
+ Valid = P;
}
+
+ EmitBinOpCheck(Valid, Ops);
}
// OpenCL 6.3j: shift values are effectively % word size of LHS.
if (CGF.getLangOpts().OpenCL)
Modified: cfe/trunk/test/CodeGen/catch-undef-behavior.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/catch-undef-behavior.c?rev=176056&r1=176055&r2=176056&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/catch-undef-behavior.c (original)
+++ cfe/trunk/test/CodeGen/catch-undef-behavior.c Mon Feb 25 16:37:49 2013
@@ -8,8 +8,7 @@
// FIXME: When we only emit each type once, use [[INT]] more below.
// CHECK: @[[LINE_100:.*]] = private unnamed_addr global {{.*}}, i32 100, i32 5 {{.*}} @[[INT]], i64 4, i8 1
// CHECK: @[[LINE_200:.*]] = {{.*}}, i32 200, i32 10 {{.*}}, i64 4, i8 0
-// CHECK: @[[LINE_300_A:.*]] = {{.*}}, i32 300, i32 12 {{.*}} @{{.*}}, {{.*}} @{{.*}}
-// CHECK: @[[LINE_300_B:.*]] = {{.*}}, i32 300, i32 12 {{.*}} @{{.*}}, {{.*}} @{{.*}}
+// CHECK: @[[LINE_300:.*]] = {{.*}}, i32 300, i32 12 {{.*}} @{{.*}}, {{.*}} @{{.*}}
// CHECK: @[[LINE_400:.*]] = {{.*}}, i32 400, i32 12 {{.*}} @{{.*}}, {{.*}} @{{.*}}
// CHECK: @[[LINE_500:.*]] = {{.*}}, i32 500, i32 10 {{.*}} @{{.*}}, i64 4, i8 0 }
// CHECK: @[[LINE_600:.*]] = {{.*}}, i32 600, i32 3 {{.*}} @{{.*}}, i64 4, i8 1 }
@@ -106,35 +105,36 @@ int addr_space(int __attribute__((addres
// CHECK-TRAP: @lsh_overflow
int lsh_overflow(int a, int b) {
// CHECK: %[[INBOUNDS:.*]] = icmp ule i32 %[[RHS:.*]], 31
- // CHECK-NEXT: br i1 %[[INBOUNDS]]
+ // CHECK-NEXT: br i1 %[[INBOUNDS]], label %[[CHECKBB:.*]], label %[[CONTBB:.*]]
// CHECK-TRAP: %[[INBOUNDS:.*]] = icmp ule i32 %[[RHS:.*]], 31
- // CHECK-TRAP-NEXT: br i1 %[[INBOUNDS]]
-
- // FIXME: Only emit one trap block here.
- // CHECK: %[[ARG1:.*]] = zext
- // CHECK-NEXT: %[[ARG2:.*]] = zext
- // CHECK-NEXT: call void @__ubsan_handle_shift_out_of_bounds(i8* bitcast ({{.*}} @[[LINE_300_A]] to i8*), i64 %[[ARG1]], i64 %[[ARG2]])
-
- // CHECK-TRAP: call void @llvm.trap() [[NR_NUW]]
- // CHECK-TRAP-NEXT: unreachable
+ // CHECK-TRAP-NEXT: br i1 %[[INBOUNDS]], label %[[CHECKBB:.*]], label %[[CONTBB:.*]]
// CHECK: %[[SHIFTED_OUT_WIDTH:.*]] = sub nuw nsw i32 31, %[[RHS]]
// CHECK-NEXT: %[[SHIFTED_OUT:.*]] = lshr i32 %[[LHS:.*]], %[[SHIFTED_OUT_WIDTH]]
// CHECK-NEXT: %[[NO_OVERFLOW:.*]] = icmp eq i32 %[[SHIFTED_OUT]], 0
- // CHECK-NEXT: br i1 %[[NO_OVERFLOW]], {{.*}} !prof ![[WEIGHT_MD]]
+ // CHECK-NEXT: br label %[[CONTBB]]
// CHECK-TRAP: %[[SHIFTED_OUT_WIDTH:.*]] = sub nuw nsw i32 31, %[[RHS]]
// CHECK-TRAP-NEXT: %[[SHIFTED_OUT:.*]] = lshr i32 %[[LHS:.*]], %[[SHIFTED_OUT_WIDTH]]
// CHECK-TRAP-NEXT: %[[NO_OVERFLOW:.*]] = icmp eq i32 %[[SHIFTED_OUT]], 0
- // CHECK-TRAP-NEXT: br i1 %[[NO_OVERFLOW]]
+ // CHECK-TRAP-NEXT: br label %[[CONTBB]]
+
+ // CHECK: %[[VALID:.*]] = phi i1 [ %[[INBOUNDS]], {{.*}} ], [ %[[NO_OVERFLOW]], %[[CHECKBB]] ]
+ // CHECK-NEXT: br i1 %[[VALID]], {{.*}} !prof ![[WEIGHT_MD]]
+
+ // CHECK-TRAP: %[[VALID:.*]] = phi i1 [ %[[INBOUNDS]], {{.*}} ], [ %[[NO_OVERFLOW]], %[[CHECKBB]] ]
+ // CHECK-TRAP-NEXT: br i1 %[[VALID]]
+
// CHECK: %[[ARG1:.*]] = zext
// CHECK-NEXT: %[[ARG2:.*]] = zext
- // CHECK-NEXT: call void @__ubsan_handle_shift_out_of_bounds(i8* bitcast ({{.*}} @[[LINE_300_B]] to i8*), i64 %[[ARG1]], i64 %[[ARG2]])
+ // CHECK-NEXT: call void @__ubsan_handle_shift_out_of_bounds(i8* bitcast ({{.*}} @[[LINE_300]] to i8*), i64 %[[ARG1]], i64 %[[ARG2]])
+ // CHECK-NOT: call void @__ubsan_handle_shift_out_of_bounds
// CHECK-TRAP: call void @llvm.trap() [[NR_NUW]]
- // CHECK-TRAP-NEXT: unreachable
+ // CHECK-TRAP: unreachable
+ // CHECK-TRAP-NOT: call void @llvm.trap()
// CHECK: %[[RET:.*]] = shl i32 %[[LHS]], %[[RHS]]
// CHECK-NEXT: ret i32 %[[RET]]
Modified: cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp?rev=176056&r1=176055&r2=176056&view=diff
==============================================================================
--- cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp (original)
+++ cfe/trunk/test/CodeGenCXX/catch-undef-behavior.cpp Mon Feb 25 16:37:49 2013
@@ -130,7 +130,12 @@ int lsh_overflow(int a, int b) {
// CHECK-NEXT: %[[SHIFTED_OUT_NOT_SIGN:.*]] = lshr i32 %[[SHIFTED_OUT]], 1
// CHECK-NEXT: %[[NO_OVERFLOW:.*]] = icmp eq i32 %[[SHIFTED_OUT_NOT_SIGN]], 0
- // CHECK-NEXT: br i1 %[[NO_OVERFLOW]]
+
+ // CHECK: %[[VALID:.*]] = phi i1 [ %[[INBOUNDS]], {{.*}} ], [ %[[NO_OVERFLOW]], {{.*}} ]
+ // CHECK-NEXT: br i1 %[[VALID]]
+
+ // CHECK: call void @__ubsan_handle_shift_out_of_bounds
+ // CHECK-NOT: call void @__ubsan_handle_shift_out_of_bounds
// CHECK: %[[RET:.*]] = shl i32 %[[LHS]], %[[RHS]]
// CHECK-NEXT: ret i32 %[[RET]]
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