[AVR] Expand 8/16-bit multiplication to libcalls on MCUs that don't have hardware MUL
This change modifies the LLVM ISel lowering settings so that
8-bit/16-bit multiplication is expanded to calls into the compiler
runtime library if the MCU being targeted does not support
multiplication in hardware.
Before this, MUL instructions would be generated on CPUs like the
ATtiny85, triggering a CPU reset due to an illegal instruction at
runtime.
First raised in https://github.com/avr-rust/rust/issues/124.
llvm-svn: 351523
diff --git a/llvm/lib/Target/AVR/AVRSubtarget.cpp b/llvm/lib/Target/AVR/AVRSubtarget.cpp
index 556d69e..c7c5662 100644
--- a/llvm/lib/Target/AVR/AVRSubtarget.cpp
+++ b/llvm/lib/Target/AVR/AVRSubtarget.cpp
@@ -29,9 +29,9 @@
namespace llvm {
AVRSubtarget::AVRSubtarget(const Triple &TT, const std::string &CPU,
- const std::string &FS, AVRTargetMachine &TM)
+ const std::string &FS, const AVRTargetMachine &TM)
: AVRGenSubtargetInfo(TT, CPU, FS), InstrInfo(), FrameLowering(),
- TLInfo(TM), TSInfo(),
+ TLInfo(TM, initializeSubtargetDependencies(CPU, FS, TM)), TSInfo(),
// Subtarget features
m_hasSRAM(false), m_hasJMPCALL(false), m_hasIJMPCALL(false),
@@ -44,4 +44,12 @@
ParseSubtargetFeatures(CPU, FS);
}
+AVRSubtarget &
+AVRSubtarget::initializeSubtargetDependencies(StringRef CPU, StringRef FS,
+ const TargetMachine &TM) {
+ // Parse features string.
+ ParseSubtargetFeatures(CPU, FS);
+ return *this;
+}
+
} // end of namespace llvm