-fcatch-undefined-behavior: add the -ftrapv checks to the set of things caught

by this mode, and also check for signed left shift overflow. The rules for the
latter are a little subtle:

 * neither C89 nor C++98 specify the behavior of a signed left shift at all
 * in C99 and C11, shifting a 1 bit into the sign bit has undefined behavior
 * in C++11, with core issue 1457, shifting a 1 bit *out* of the sign bit has
   undefined behavior

As of this change, we use the C99 rules for all C language variants, and the
C++11 rules for all C++ language variants. Once we have individual
-fcatch-undefined-behavior= flags, this should be revisited.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162634 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 55 insertions, 0 deletions

diff --git a/test/CodeGen/catch-undef-behavior.c b/test/CodeGen/catch-undef-behavior.c
index 8c45fa5045..5832b6c830 100644
--- a/test/CodeGen/catch-undef-behavior.c
+++ b/test/CodeGen/catch-undef-behavior.c
@@ -19,3 +19,28 @@ int bar(int *a) {
   // CHECK-NEXT: icmp eq i64 %[[MISALIGN]], 0
   return *a;
 }
+
+// CHECK: @lsh_overflow
+int lsh_overflow(int a, int b) {
+  // CHECK: %[[INBOUNDS:.*]] = icmp ule i32 %[[RHS:.*]], 31
+  // CHECK-NEXT: br i1 %[[INBOUNDS]]
+
+  // 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]]
+
+  // CHECK: %[[RET:.*]] = shl i32 %[[LHS]], %[[RHS]]
+  // CHECK-NEXT: ret i32 %[[RET]]
+  return a << b;
+}
+
+// CHECK: @rsh_inbounds
+int rsh_inbounds(int a, int b) {
+  // CHECK: %[[INBOUNDS:.*]] = icmp ult i32 %[[RHS:.*]], 32
+  // CHECK: br i1 %[[INBOUNDS]]
+
+  // CHECK: %[[RET:.*]] = ashr i32 %[[LHS]], %[[RHS]]
+  // CHECK-NEXT: ret i32 %[[RET]]
+  return a >> b;
+}
diff --git a/test/CodeGen/integer-overflow.c b/test/CodeGen/integer-overflow.c
index d7fff4ee4a..176ee65ff5 100644
--- a/test/CodeGen/integer-overflow.c
+++ b/test/CodeGen/integer-overflow.c
@@ -1,6 +1,7 @@
 // RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - | FileCheck %s --check-prefix=DEFAULT
 // RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - -fwrapv | FileCheck %s --check-prefix=WRAPV
 // RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - -ftrapv | FileCheck %s --check-prefix=TRAPV
+// RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - -fcatch-undefined-behavior | FileCheck %s --check-prefix=CATCH_UB
 // RUN: %clang_cc1 -triple x86_64-apple-darwin %s -emit-llvm -o - -ftrapv -ftrapv-handler foo | FileCheck %s --check-prefix=TRAPV_HANDLER
 
 
@@ -15,24 +16,28 @@ void test1() {
   // DEFAULT: add nsw i32
   // WRAPV: add i32
   // TRAPV: llvm.sadd.with.overflow.i32
+  // CATCH_UB: llvm.sadd.with.overflow.i32
   // TRAPV_HANDLER: foo(
   f11G = a + b;
   
   // DEFAULT: sub nsw i32
   // WRAPV: sub i32
   // TRAPV: llvm.ssub.with.overflow.i32
+  // CATCH_UB: llvm.ssub.with.overflow.i32
   // TRAPV_HANDLER: foo(
   f11G = a - b;
   
   // DEFAULT: mul nsw i32
   // WRAPV: mul i32
   // TRAPV: llvm.smul.with.overflow.i32
+  // CATCH_UB: llvm.smul.with.overflow.i32
   // TRAPV_HANDLER: foo(
   f11G = a * b;
 
   // DEFAULT: sub nsw i32 0, 
   // WRAPV: sub i32 0, 
   // TRAPV: llvm.ssub.with.overflow.i32(i32 0
+  // CATCH_UB: llvm.ssub.with.overflow.i32(i32 0
   // TRAPV_HANDLER: foo(
   f11G = -a;
   
@@ -41,12 +46,14 @@ void test1() {
   // DEFAULT: add nsw i32 {{.*}}, 1
   // WRAPV: add i32 {{.*}}, 1
   // TRAPV: llvm.sadd.with.overflow.i32({{.*}}, i32 1)
+  // CATCH_UB: llvm.sadd.with.overflow.i32({{.*}}, i32 1)
   // TRAPV_HANDLER: foo(
   ++a;
   
   // DEFAULT: add nsw i32 {{.*}}, -1
   // WRAPV: add i32 {{.*}}, -1
   // TRAPV: llvm.sadd.with.overflow.i32({{.*}}, i32 -1)
+  // CATCH_UB: llvm.sadd.with.overflow.i32({{.*}}, i32 -1)
   // TRAPV_HANDLER: foo(
   --a;
   
@@ -56,11 +63,13 @@ void test1() {
   // DEFAULT: getelementptr inbounds i32*
   // WRAPV: getelementptr i32*
   // TRAPV: getelementptr inbounds i32*
+  // CATCH_UB: getelementptr inbounds i32*
 
   // PR9350: char increment never overflows.
   extern volatile signed char PR9350;
   // DEFAULT: add i8 {{.*}}, 1
   // WRAPV: add i8 {{.*}}, 1
   // TRAPV: add i8 {{.*}}, 1
+  // CATCH_UB: add i8 {{.*}}, 1
   ++PR9350;
 }
diff --git a/test/CodeGen/trapv.c b/test/CodeGen/trapv.c
index f52dad5564..abad5850b4 100644
--- a/test/CodeGen/trapv.c
+++ b/test/CodeGen/trapv.c
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-apple-darwin10 -ftrapv %s -emit-llvm -o - | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fcatch-undefined-behavior %s -emit-llvm -o - | FileCheck %s
 
 unsigned int ui, uj, uk;
 int i, j, k;
diff --git a/test/CodeGenCXX/catch-undef-behavior.cpp b/test/CodeGenCXX/catch-undef-behavior.cpp
index ed0a7763f5..0ec1cc1e05 100644
--- a/test/CodeGenCXX/catch-undef-behavior.cpp
+++ b/test/CodeGenCXX/catch-undef-behavior.cpp
@@ -66,3 +66,23 @@ void member_access(S *p) {
   // CHECK-NEXT: icmp eq i64 %[[MISALIGN]], 0
   k = p->f();
 }
+
+// CHECK: @_Z12lsh_overflow
+int lsh_overflow(int a, int b) {
+  // CHECK: %[[INBOUNDS:.*]] = icmp ule i32 %[[RHS:.*]], 31
+  // CHECK-NEXT: br i1 %[[INBOUNDS]]
+
+  // CHECK: %[[SHIFTED_OUT_WIDTH:.*]] = sub nuw nsw i32 31, %[[RHS]]
+  // CHECK-NEXT: %[[SHIFTED_OUT:.*]] = lshr i32 %[[LHS:.*]], %[[SHIFTED_OUT_WIDTH]]
+
+  // This is present for C++11 but not for C: C++ core issue 1457 allows a '1'
+  // to be shifted into the sign bit, but not out of it.
+  // 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: %[[RET:.*]] = shl i32 %[[LHS]], %[[RHS]]
+  // CHECK-NEXT: ret i32 %[[RET]]
+  return a << b;
+}