This pass, fixing an erratum in some LEON 2 processors ensures that the SDIV instruction is not issued, but replaced by SDIVcc instead, which does not exhibit the error. Unit test included.
Differential Review: https://reviews.llvm.org/D24660
llvm-svn: 283727
diff --git a/llvm/lib/Target/Sparc/LeonFeatures.td b/llvm/lib/Target/Sparc/LeonFeatures.td
index e2282ab..27d739b 100755
--- a/llvm/lib/Target/Sparc/LeonFeatures.td
+++ b/llvm/lib/Target/Sparc/LeonFeatures.td
@@ -37,6 +37,14 @@
"Enable CASA instruction for LEON3 and LEON4 processors"
>;
+
+def ReplaceSDIV : SubtargetFeature<
+ "replacesdiv",
+ "PerformSDIVReplace",
+ "true",
+ "AT697E erratum fix: Do not emit SDIV, emit SDIVCC instead"
+>;
+
def InsertNOPLoad: SubtargetFeature<
"insertnopload",
"InsertNOPLoad",
diff --git a/llvm/lib/Target/Sparc/Sparc.td b/llvm/lib/Target/Sparc/Sparc.td
index bdbdc1c..11004c5 100644
--- a/llvm/lib/Target/Sparc/Sparc.td
+++ b/llvm/lib/Target/Sparc/Sparc.td
@@ -110,7 +110,7 @@
// LEON 2 FT (AT697E)
// TO DO: Place-holder: Processor specific features will be added *very* soon here.
def : Processor<"at697e", LEON2Itineraries,
- [FeatureLeon, InsertNOPLoad]>;
+ [FeatureLeon, ReplaceSDIV, InsertNOPLoad]>;
// LEON 2 FT (AT697F)
// TO DO: Place-holder: Processor specific features will be added *very* soon here.
diff --git a/llvm/lib/Target/Sparc/SparcISelDAGToDAG.cpp b/llvm/lib/Target/Sparc/SparcISelDAGToDAG.cpp
index a16cd32..c36e75d 100644
--- a/llvm/lib/Target/Sparc/SparcISelDAGToDAG.cpp
+++ b/llvm/lib/Target/Sparc/SparcISelDAGToDAG.cpp
@@ -360,6 +360,12 @@
// FIXME: Handle div by immediate.
unsigned Opcode = N->getOpcode() == ISD::SDIV ? SP::SDIVrr : SP::UDIVrr;
+ // SDIV is a hardware erratum on some LEON2 processors. Replace it with SDIVcc here.
+ if (((SparcTargetMachine&)TM).getSubtargetImpl()->performSDIVReplace()
+ &&
+ Opcode == SP::SDIVrr) {
+ Opcode = SP::SDIVCCrr;
+ }
CurDAG->SelectNodeTo(N, Opcode, MVT::i32, DivLHS, DivRHS, TopPart);
return;
}
diff --git a/llvm/lib/Target/Sparc/SparcSubtarget.cpp b/llvm/lib/Target/Sparc/SparcSubtarget.cpp
index 97d4aef..75ea4c7 100644
--- a/llvm/lib/Target/Sparc/SparcSubtarget.cpp
+++ b/llvm/lib/Target/Sparc/SparcSubtarget.cpp
@@ -39,6 +39,7 @@
// Leon features
HasLeonCasa = false;
HasUmacSmac = false;
+ PerformSDIVReplace = false;
InsertNOPLoad = false;
FixFSMULD = false;
ReplaceFMULS = false;
diff --git a/llvm/lib/Target/Sparc/SparcSubtarget.h b/llvm/lib/Target/Sparc/SparcSubtarget.h
index 9122f54..25dc429 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 PerformSDIVReplace;
SparcInstrInfo InstrInfo;
SparcTargetLowering TLInfo;
@@ -86,6 +87,7 @@
// Leon options
bool hasUmacSmac() const { return HasUmacSmac; }
+ bool performSDIVReplace() const { return PerformSDIVReplace; }
bool hasLeonCasa() const { return HasLeonCasa; }
bool insertNOPLoad() const { return InsertNOPLoad; }
bool fixFSMULD() const { return FixFSMULD; }