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Much improved pic jumptable codegen:

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Then:
        call    "L1$pb"
"L1$pb":
        popl    %eax
		...
LBB1_1: # entry
        imull   $4, %ecx, %ecx
        leal    LJTI1_0-"L1$pb"(%eax), %edx
        addl    LJTI1_0-"L1$pb"(%ecx,%eax), %edx
        jmpl    *%edx

        .align  2
        .set L1_0_set_3,LBB1_3-LJTI1_0
        .set L1_0_set_2,LBB1_2-LJTI1_0
        .set L1_0_set_5,LBB1_5-LJTI1_0
        .set L1_0_set_4,LBB1_4-LJTI1_0
LJTI1_0:
        .long    L1_0_set_3
        .long    L1_0_set_2

Now:
        call    "L1$pb"
"L1$pb":
        popl    %eax
		...
LBB1_1: # entry
        addl    LJTI1_0-"L1$pb"(%eax,%ecx,4), %eax
        jmpl    *%eax

		.align  2
		.set L1_0_set_3,LBB1_3-"L1$pb"
		.set L1_0_set_2,LBB1_2-"L1$pb"
		.set L1_0_set_5,LBB1_5-"L1$pb"
		.set L1_0_set_4,LBB1_4-"L1$pb"
LJTI1_0:
        .long    L1_0_set_3
        .long    L1_0_set_2


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43924 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2007-11-09 01:32:10 +00:00
parent 2dfdefd282
commit cc41586b9d
12 changed files with 87 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
lib/CodeGen/AsmPrinter.cpp
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@ -26,6 +26,7 @@
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/ADT/SmallPtrSet.h"
#include <cerrno>
using namespace llvm;
@ -282,11 +283,11 @@ void AsmPrinter::EmitJumpTableInfo(MachineJumpTableInfo *MJTI,
// For PIC codegen, if possible we want to use the SetDirective to reduce
// the number of relocations the assembler will generate for the jump table.
// Set directives are all printed before the jump table itself.
std::set<MachineBasicBlock*> EmittedSets;
SmallPtrSet<MachineBasicBlock*, 16> EmittedSets;
if (TAI->getSetDirective() && IsPic)
for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii)
if (EmittedSets.insert(JTBBs[ii]).second)
printSetLabel(i, JTBBs[ii]);
if (EmittedSets.insert(JTBBs[ii]))
printPICJumpTableSetLabel(i, JTBBs[ii]);
// On some targets (e.g. darwin) we want to emit two consequtive labels
// before each jump table. The first label is never referenced, but tells
@ -1256,10 +1257,10 @@ void AsmPrinter::printBasicBlockLabel(const MachineBasicBlock *MBB,
<< MBB->getBasicBlock()->getName();
}
/// printSetLabel - This method prints a set label for the specified
/// MachineBasicBlock
void AsmPrinter::printSetLabel(unsigned uid,
const MachineBasicBlock *MBB) const {
/// printPICJumpTableSetLabel - This method prints a set label for the
/// specified MachineBasicBlock for a jumptable entry.
void AsmPrinter::printPICJumpTableSetLabel(unsigned uid,
const MachineBasicBlock *MBB) const {
if (!TAI->getSetDirective())
return;
@ -1270,8 +1271,8 @@ void AsmPrinter::printSetLabel(unsigned uid,
<< '_' << uid << '\n';
}
void AsmPrinter::printSetLabel(unsigned uid, unsigned uid2,
const MachineBasicBlock *MBB) const {
void AsmPrinter::printPICJumpTableSetLabel(unsigned uid, unsigned uid2,
const MachineBasicBlock *MBB) const {
if (!TAI->getSetDirective())
return;