Changes in directory llvm/lib/Target/ARM:
ARMConstantIslandPass.cpp updated: 1.19 -> 1.20
---
Log message:
- Off by one bugs in maximum displacement calculation / testing.
- In thumb mode, a new constpool island BB size should be 4 + 2 to
compensate for the potential padding due to alignment requirement.
---
Diffs of the changes: (+28 -15)
ARMConstantIslandPass.cpp | 43 ++++++++++++++++++++++++++++---------------
1 files changed, 28 insertions(+), 15 deletions(-)
Index: llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
diff -u llvm/lib/Target/ARM/ARMConstantIslandPass.cpp:1.19
llvm/lib/Target/ARM/ARMConstantIslandPass.cpp:1.20
--- llvm/lib/Target/ARM/ARMConstantIslandPass.cpp:1.19 Wed Jan 31 19:09:47 2007
+++ llvm/lib/Target/ARM/ARMConstantIslandPass.cpp Thu Feb 1 04:16:15 2007
@@ -281,8 +281,10 @@
Scale = 2;
break;
}
- unsigned MaxDisp = (1 << (Bits-1)) * Scale;
- ImmBranches.push_back(ImmBranch(I, MaxDisp, isCond, UOpc));
+
+ // Record this immediate branch.
+ unsigned MaxOffs = (1 << (Bits-1)) * Scale;
+ ImmBranches.push_back(ImmBranch(I, MaxOffs, isCond, UOpc));
}
if (Opc == ARM::tPUSH || Opc == ARM::tPOP_RET)
@@ -293,9 +295,10 @@
if (I->getOperand(op).isConstantPoolIndex()) {
// We found one. The addressing mode tells us the max displacement
// from the PC that this instruction permits.
- unsigned MaxOffs = 0;
// Basic size info comes from the TSFlags field.
+ unsigned Bits = 0;
+ unsigned Scale = 1;
unsigned TSFlags = I->getInstrDescriptor()->TSFlags;
switch (TSFlags & ARMII::AddrModeMask) {
default:
@@ -304,34 +307,42 @@
continue;
assert(0 && "Unknown addressing mode for CP reference!");
case ARMII::AddrMode1: // AM1: 8 bits << 2
- MaxOffs = 1 << (8+2); // Taking the address of a CP entry.
+ Bits = 8;
+ Scale = 4; // Taking the address of a CP entry.
break;
case ARMII::AddrMode2:
- MaxOffs = 1 << 12; // +-offset_12
+ Bits = 12;
+ Scale = 2; // +-offset_12
break;
case ARMII::AddrMode3:
- MaxOffs = 1 << 8; // +-offset_8
+ Bits = 8;
+ Scale = 2; // +-offset_8
break;
// addrmode4 has no immediate offset.
case ARMII::AddrMode5:
- MaxOffs = 1 << (8+2); // +-(offset_8*4)
+ Bits = 8;
+ Scale = 4; // +-(offset_8*4)
break;
case ARMII::AddrModeT1:
- MaxOffs = 1 << 5;
+ Bits = 5; // +offset_5
break;
case ARMII::AddrModeT2:
- MaxOffs = 1 << (5+1);
+ Bits = 5;
+ Scale = 2; // +(offset_5*2)
break;
case ARMII::AddrModeT4:
- MaxOffs = 1 << (5+2);
+ Bits = 5;
+ Scale = 4; // +(offset_5*4)
break;
case ARMII::AddrModeTs:
- MaxOffs = 1 << (8+2);
+ Bits = 8;
+ Scale = 4; // +(offset_8*4)
break;
}
-
+
// Remember that this is a user of a CP entry.
MachineInstr *CPEMI
=CPEMIs[I->getOperand(op).getConstantPoolIndex()];
+ unsigned MaxOffs = (1 << (Bits-1)) * Scale;
CPUsers.push_back(CPUser(I, CPEMI, MaxOffs));
// Instructions can only use one CP entry, don't bother scanning the
@@ -514,12 +525,12 @@
// TODO: Search for the best place to split the code. In practice, using
// loop nesting information to insert these guys outside of loops would be
// sufficient.
+ bool isThumb = AFI->isThumbFunction();
if (&UserMBB->back() == UserMI) {
assert(BBHasFallthrough(UserMBB) && "Expected a fallthrough BB!");
NewMBB = next(MachineFunction::iterator(UserMBB));
// Add an unconditional branch from UserMBB to fallthrough block.
// Note the new unconditional branch is not being recorded.
- bool isThumb = AFI->isThumbFunction();
BuildMI(UserMBB, TII->get(isThumb ? ARM::tB : ARM::B)).addMBB(NewMBB);
BBSizes[UserMBB->getNumber()] += isThumb ? 2 : 4;
} else {
@@ -539,11 +550,13 @@
unsigned ID = NextUID++;
unsigned CPI = CPEMI->getOperand(1).getConstantPoolIndex();
unsigned Size = CPEMI->getOperand(2).getImm();
-
+
// Build a new CPE for this user.
U.CPEMI = BuildMI(NewIsland, TII->get(ARM::CONSTPOOL_ENTRY))
.addImm(ID).addConstantPoolIndex(CPI).addImm(Size);
+ // Compensate for .align 2 in thumb mode.
+ if (isThumb) Size += 2;
// Increase the size of the island block to account for the new entry.
BBSizes[NewIsland->getNumber()] += Size;
@@ -574,7 +587,7 @@
<< *MI);
if (BrOffset <= DestOffset) {
- if (DestOffset - BrOffset < MaxDisp)
+ if (DestOffset - BrOffset <= MaxDisp)
return true;
} else {
if (BrOffset - DestOffset <= MaxDisp)
_______________________________________________
llvm-commits mailing list
llvm-commits@cs.uiuc.edu
http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
