In the CBackend, use casts to force integer add, subtract, and
multiply to be done as unsigned, so that they have well defined
behavior on overflow. This fixes PR2408.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53767 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/CBackend/CBackend.cpp b/lib/Target/CBackend/CBackend.cpp
index 71895f4..34511e8 100644
--- a/lib/Target/CBackend/CBackend.cpp
+++ b/lib/Target/CBackend/CBackend.cpp
@@ -1116,6 +1116,13 @@
const Type *Ty = CE->getOperand(0)->getType();
bool TypeIsSigned = false;
switch (CE->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // We need to cast integer arithmetic so that it is always performed
+ // as unsigned, to avoid undefined behavior on overflow.
+ if (!Ty->isIntOrIntVector()) break;
+ // FALL THROUGH
case Instruction::LShr:
case Instruction::URem:
case Instruction::UDiv: NeedsExplicitCast = true; break;
@@ -1174,6 +1181,13 @@
default:
// for most instructions, it doesn't matter
break;
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // We need to cast integer arithmetic so that it is always performed
+ // as unsigned, to avoid undefined behavior on overflow.
+ if (!OpTy->isIntOrIntVector()) break;
+ // FALL THROUGH
case Instruction::LShr:
case Instruction::UDiv:
case Instruction::URem:
@@ -1294,6 +1308,13 @@
bool CWriter::writeInstructionCast(const Instruction &I) {
const Type *Ty = I.getOperand(0)->getType();
switch (I.getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // We need to cast integer arithmetic so that it is always performed
+ // as unsigned, to avoid undefined behavior on overflow.
+ if (!Ty->isIntOrIntVector()) break;
+ // FALL THROUGH
case Instruction::LShr:
case Instruction::URem:
case Instruction::UDiv:
@@ -1334,6 +1355,13 @@
default:
// for most instructions, it doesn't matter
break;
+ case Instruction::Add:
+ case Instruction::Sub:
+ case Instruction::Mul:
+ // We need to cast integer arithmetic so that it is always performed
+ // as unsigned, to avoid undefined behavior on overflow.
+ if (!OpTy->isIntOrIntVector()) break;
+ // FALL THROUGH
case Instruction::LShr:
case Instruction::UDiv:
case Instruction::URem: // Cast to unsigned first
diff --git a/test/CodeGen/CBackend/2007-02-23-NameConflicts.ll b/test/CodeGen/CBackend/2007-02-23-NameConflicts.ll
index 2bc4d51..eb5cb86 100644
--- a/test/CodeGen/CBackend/2007-02-23-NameConflicts.ll
+++ b/test/CodeGen/CBackend/2007-02-23-NameConflicts.ll
@@ -1,7 +1,8 @@
; PR1164
; RUN: llvm-as < %s | llc -march=c | grep {llvm_cbe_A = \\*llvm_cbe_G;}
; RUN: llvm-as < %s | llc -march=c | grep {llvm_cbe_B = \\*(<mp_0_1);}
-; RUN: llvm-as < %s | llc -march=c | grep {return (llvm_cbe_A + llvm_cbe_B);}
+; RUN: llvm-as < %s | llc -march=c | grep {return (((unsigned int )(((unsigned int )llvm_cbe_A) + ((unsigned int )llvm_cbe_B))));}
+
@G = global i32 123
@ltmp_0_1 = global i32 123
diff --git a/test/CodeGen/CBackend/pr2408.ll b/test/CodeGen/CBackend/pr2408.ll
new file mode 100644
index 0000000..a16f91b
--- /dev/null
+++ b/test/CodeGen/CBackend/pr2408.ll
@@ -0,0 +1,12 @@
+; RUN: llvm-as < %s | llc -march=c | grep {\\* ((unsigned int )}
+; PR2408
+
+define i32 @a(i32 %a) {
+entry:
+ %shr = ashr i32 %a, 0 ; <i32> [#uses=1]
+ %shr2 = ashr i32 2, 0 ; <i32> [#uses=1]
+ %mul = mul i32 %shr, %shr2 ; <i32> [#uses=1]
+ %shr4 = ashr i32 2, 0 ; <i32> [#uses=1]
+ %div = sdiv i32 %mul, %shr4 ; <i32> [#uses=1]
+ ret i32 %div
+}