Add an option to use a virtual register as the global base register instead of
reserving a physical register ($gp or $28) for that purpose.
This will completely eliminate loads that restore the value of $gp after every
function call, if the register allocator assigns a callee-saved register, or
eliminate unnecessary loads if it assigns a temporary register.
example:
.cpload $25 // set $gp.
...
.cprestore 16 // store $gp to stack slot 16($sp).
...
jalr $25 // function call. clobbers $gp.
lw $gp, 16($sp) // not emitted if callee-saved reg is chosen.
...
lw $2, 4($gp)
...
jalr $25 // function call.
lw $gp, 16($sp) // not emitted if $gp is not live after this instruction.
...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151402 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/Mips/MipsAsmPrinter.cpp b/lib/Target/Mips/MipsAsmPrinter.cpp
index 9ddc08a..f83cb9a 100644
--- a/lib/Target/Mips/MipsAsmPrinter.cpp
+++ b/lib/Target/Mips/MipsAsmPrinter.cpp
@@ -34,6 +34,8 @@
#include "llvm/Instructions.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCInst.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/TargetRegistry.h"
@@ -116,6 +118,16 @@
}
}
+ if (Opc == Mips::SETGP01) {
+ MCInstLowering.LowerSETGP01(MI, MCInsts);
+
+ for (SmallVector<MCInst, 4>::iterator I = MCInsts.begin();
+ I != MCInsts.end(); ++I)
+ OutStreamer.EmitInstruction(*I);
+
+ return;
+ }
+
OutStreamer.EmitInstruction(TmpInst0);
}