Bypass Slow Divides
* Only apply divide bypass optimization when not optimizing for size.
* Fixed bug caused by constant for 0 value of type Int32,
used dividend type to generate the constant instead.
* For atom x86-64 apply the divide bypass to use 16-bit divides instead of
64-bit divides when operand values are small enough.
* Added lit tests for 64-bit divide bypass.
Patch by Tyler Nowicki!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176442 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 451acca..5d12b0a 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -181,9 +181,12 @@
setSchedulingPreference(Sched::RegPressure);
setStackPointerRegisterToSaveRestore(RegInfo->getStackRegister());
- // Bypass i32 with i8 on Atom when compiling with O2
- if (Subtarget->hasSlowDivide() && TM.getOptLevel() >= CodeGenOpt::Default)
+ // Bypass expensive divides on Atom when compiling with O2
+ if (Subtarget->hasSlowDivide() && TM.getOptLevel() >= CodeGenOpt::Default) {
addBypassSlowDiv(32, 8);
+ if (Subtarget->is64Bit())
+ addBypassSlowDiv(64, 16);
+ }
if (Subtarget->isTargetWindows() && !Subtarget->isTargetCygMing()) {
// Setup Windows compiler runtime calls.