[TTI] Make the cost APIs in TargetTransformInfo consistently use 'int'

rather than 'unsigned' for their costs.

For something like costs in particular there is a natural "negative"
value, that of savings or saved cost. As a consequence, there is a lot
of code that subtracts or creates negative values based on cost, all of
which is prone to awkwardness or bugs when dealing with an unsigned
type. Similarly, we *never* want these values to wrap, as that would
cause Very Bad code generation (likely percieved as an infinite loop as
we try to emit over 2^32 instructions or some such insanity).

All around 'int' seems a much better fit for these basic metrics. I've
added asserts to ensure that at least the TTI interface never returns
negative numbers here. If we ever have a use case for negative numbers,
we can remove this, but this way a bug where someone used '-1' to
produce a 'very large' cost will be caught by the assert.

This passes all tests, and is also UBSan clean.

No functional change intended.

Differential Revision: http://reviews.llvm.org/D11741

llvm-svn: 244080

1 files changed, 5 insertions, 5 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp b/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
index 5a87df1976c..5ff5b21f49b 100644
--- a/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
@@ -31,7 +31,7 @@ using namespace llvm;
 //
 //===----------------------------------------------------------------------===//
 
-unsigned SystemZTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
+int SystemZTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
   assert(Ty->isIntegerTy());
 
   unsigned BitSize = Ty->getPrimitiveSizeInBits();
@@ -63,8 +63,8 @@ unsigned SystemZTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
   return 4 * TTI::TCC_Basic;
 }
 
-unsigned SystemZTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx,
-                                       const APInt &Imm, Type *Ty) {
+int SystemZTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx,
+                                  const APInt &Imm, Type *Ty) {
   assert(Ty->isIntegerTy());
 
   unsigned BitSize = Ty->getPrimitiveSizeInBits();
@@ -181,8 +181,8 @@ unsigned SystemZTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx,
   return SystemZTTIImpl::getIntImmCost(Imm, Ty);
 }
 
-unsigned SystemZTTIImpl::getIntImmCost(Intrinsic::ID IID, unsigned Idx,
-                                       const APInt &Imm, Type *Ty) {
+int SystemZTTIImpl::getIntImmCost(Intrinsic::ID IID, unsigned Idx,
+                                  const APInt &Imm, Type *Ty) {
   assert(Ty->isIntegerTy());
 
   unsigned BitSize = Ty->getPrimitiveSizeInBits();