[Sparc][LEON] Detects an erratum on UT699 LEON 3 processors involving rounding mode changes and issues an appropriate user error message.
Differential Revision: https://reviews.llvm.org/D24665
llvm-svn: 284591
diff --git a/llvm/lib/Target/Sparc/LeonFeatures.td b/llvm/lib/Target/Sparc/LeonFeatures.td
index 27d739b..d06e734 100755
--- a/llvm/lib/Target/Sparc/LeonFeatures.td
+++ b/llvm/lib/Target/Sparc/LeonFeatures.td
@@ -66,6 +66,14 @@
"LEON erratum fix: Replace FMULS instruction with FMULD and relevant conversion instructions"
>;
+def DetectRoundChange : SubtargetFeature<
+ "detectroundchange",
+ "DetectRoundChange",
+ "true",
+ "LEON3 erratum detection: Detects any rounding mode change "
+ "request: use only the round-to-nearest rounding mode"
+>;
+
def FixAllFDIVSQRT : SubtargetFeature<
"fixallfdivsqrt",
"FixAllFDIVSQRT",
diff --git a/llvm/lib/Target/Sparc/LeonPasses.cpp b/llvm/lib/Target/Sparc/LeonPasses.cpp
index 46ae9cc..0acc287 100644
--- a/llvm/lib/Target/Sparc/LeonPasses.cpp
+++ b/llvm/lib/Target/Sparc/LeonPasses.cpp
@@ -16,6 +16,7 @@
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
@@ -274,6 +275,50 @@
return Modified;
}
+
+//*****************************************************************************
+//**** DetectRoundChange pass
+//*****************************************************************************
+// To prevent any explicit change of the default rounding mode, this pass
+// detects any call of the fesetround function.
+// A warning is generated to ensure the user knows this has happened.
+//
+// Detects an erratum in UT699 LEON 3 processor
+
+char DetectRoundChange::ID = 0;
+
+DetectRoundChange::DetectRoundChange(TargetMachine &tm)
+ : LEONMachineFunctionPass(tm, ID) {}
+
+bool DetectRoundChange::runOnMachineFunction(MachineFunction &MF) {
+ Subtarget = &MF.getSubtarget<SparcSubtarget>();
+
+ bool Modified = false;
+ for (auto MFI = MF.begin(), E = MF.end(); MFI != E; ++MFI) {
+ MachineBasicBlock &MBB = *MFI;
+ for (auto MBBI = MBB.begin(), E = MBB.end(); MBBI != E; ++MBBI) {
+ MachineInstr &MI = *MBBI;
+ unsigned Opcode = MI.getOpcode();
+ if (Opcode == SP::CALL && MI.getNumOperands() > 0) {
+ MachineOperand &MO = MI.getOperand(0);
+
+ if (MO.isGlobal()) {
+ StringRef FuncName = MO.getGlobal()->getName();
+ if (FuncName.compare_lower("fesetround") == 0) {
+ errs() << "Error: You are using the detectroundchange "
+ "option to detect rounding changes that will "
+ "cause LEON errata. The only way to fix this "
+ "is to remove the call to fesetround from "
+ "the source code.\n";
+ }
+ }
+ }
+ }
+ }
+
+ return Modified;
+}
+
//*****************************************************************************
//**** FixAllFDIVSQRT pass
//*****************************************************************************
diff --git a/llvm/lib/Target/Sparc/LeonPasses.h b/llvm/lib/Target/Sparc/LeonPasses.h
index c3ff869..2158cb6 100755
--- a/llvm/lib/Target/Sparc/LeonPasses.h
+++ b/llvm/lib/Target/Sparc/LeonPasses.h
@@ -84,6 +84,20 @@
}
};
+class LLVM_LIBRARY_VISIBILITY DetectRoundChange
+ : public LEONMachineFunctionPass {
+public:
+ static char ID;
+
+ DetectRoundChange(TargetMachine &tm);
+ bool runOnMachineFunction(MachineFunction &MF) override;
+
+ StringRef getPassName() const override {
+ return "DetectRoundChange: Leon erratum detection: detect any rounding "
+ "mode change request: use only the round-to-nearest rounding mode";
+ }
+};
+
class LLVM_LIBRARY_VISIBILITY FixAllFDIVSQRT : public LEONMachineFunctionPass {
public:
static char ID;
diff --git a/llvm/lib/Target/Sparc/SparcSubtarget.cpp b/llvm/lib/Target/Sparc/SparcSubtarget.cpp
index 75ea4c7..43ddef3 100644
--- a/llvm/lib/Target/Sparc/SparcSubtarget.cpp
+++ b/llvm/lib/Target/Sparc/SparcSubtarget.cpp
@@ -44,6 +44,7 @@
FixFSMULD = false;
ReplaceFMULS = false;
FixAllFDIVSQRT = false;
+ DetectRoundChange = false;
// Determine default and user specified characteristics
std::string CPUName = CPU;
diff --git a/llvm/lib/Target/Sparc/SparcSubtarget.h b/llvm/lib/Target/Sparc/SparcSubtarget.h
index 25dc429..fa42da4 100644
--- a/llvm/lib/Target/Sparc/SparcSubtarget.h
+++ b/llvm/lib/Target/Sparc/SparcSubtarget.h
@@ -48,6 +48,7 @@
bool FixFSMULD;
bool ReplaceFMULS;
bool FixAllFDIVSQRT;
+ bool DetectRoundChange;
bool PerformSDIVReplace;
SparcInstrInfo InstrInfo;
@@ -93,6 +94,7 @@
bool fixFSMULD() const { return FixFSMULD; }
bool replaceFMULS() const { return ReplaceFMULS; }
bool fixAllFDIVSQRT() const { return FixAllFDIVSQRT; }
+ bool detectRoundChange() const { return DetectRoundChange; }
/// ParseSubtargetFeatures - Parses features string setting specified
/// subtarget options. Definition of function is auto generated by tblgen.
diff --git a/llvm/lib/Target/Sparc/SparcTargetMachine.cpp b/llvm/lib/Target/Sparc/SparcTargetMachine.cpp
index 0669eb6..4ae64062 100644
--- a/llvm/lib/Target/Sparc/SparcTargetMachine.cpp
+++ b/llvm/lib/Target/Sparc/SparcTargetMachine.cpp
@@ -157,6 +157,9 @@
{
addPass(new ReplaceFMULS(getSparcTargetMachine()));
}
+ if (this->getSparcTargetMachine().getSubtargetImpl()->detectRoundChange()) {
+ addPass(new DetectRoundChange(getSparcTargetMachine()));
+ }
if (this->getSparcTargetMachine().getSubtargetImpl()->fixAllFDIVSQRT())
{
addPass(new FixAllFDIVSQRT(getSparcTargetMachine()));