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Also shrink immediate branches; also more assembler workarounds. 

llvm-svn: 79014
This commit is contained in:
Evan Cheng 2009-08-14 18:31:44 +00:00
parent e827123f08
commit e41903b10d
4 changed files with 136 additions and 17 deletions
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61
llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
View File

@ -38,6 +38,7 @@ STATISTIC(NumCBrFixed, "Number of cond branches fixed");
STATISTIC(NumUBrFixed, "Number of uncond branches fixed");
STATISTIC(NumTBs, "Number of table branches generated");
STATISTIC(NumT2CPShrunk, "Number of Thumb2 constantpool instructions shrunk");
STATISTIC(NumT2BrShrunk, "Number of Thumb2 immediate branches shrunk");
namespace {
/// ARMConstantIslands - Due to limited PC-relative displacements, ARM
@ -479,8 +480,6 @@ void ARMConstantIslands::InitialFunctionScan(MachineFunction &MF,
bool NegOk = false;
bool IsSoImm = false;
// FIXME: Temporary workaround until I can figure out what's going on.
unsigned Slack = T2JumpTables.empty() ? 0 : 4;
switch (Opc) {
default:
llvm_unreachable("Unknown addressing mode for CP reference!");
@ -530,7 +529,7 @@ void ARMConstantIslands::InitialFunctionScan(MachineFunction &MF,
// Remember that this is a user of a CP entry.
unsigned CPI = I->getOperand(op).getIndex();
MachineInstr *CPEMI = CPEMIs[CPI];
unsigned MaxOffs = ((1 << Bits)-1) * Scale - Slack;
unsigned MaxOffs = ((1 << Bits)-1) * Scale;
CPUsers.push_back(CPUser(I, CPEMI, MaxOffs, NegOk, IsSoImm));
// Increment corresponding CPEntry reference count.
@ -714,11 +713,23 @@ bool ARMConstantIslands::OffsetIsInRange(unsigned UserOffset,
// purposes of the displacement computation; compensate for that here.
// Effectively, the valid range of displacements is 2 bytes smaller for such
// references.
if (isThumb && UserOffset%4 !=0)
unsigned TotalAdj = 0;
if (isThumb && UserOffset%4 !=0) {
UserOffset -= 2;
TotalAdj = 2;
}
// CPEs will be rounded up to a multiple of 4.
if (isThumb && TrialOffset%4 != 0)
if (isThumb && TrialOffset%4 != 0) {
TrialOffset += 2;
TotalAdj += 2;
}
// In Thumb2 mode, later branch adjustments can shift instructions up and
// cause alignment change. In the worst case scenario this can cause the
// user's effective address to be subtracted by 2 and the CPE's address to
// be plus 2.
if (isThumb2 && TotalAdj != 4)
MaxDisp -= (4 - TotalAdj);
if (UserOffset <= TrialOffset) {
// User before the Trial.
@ -1398,13 +1409,49 @@ bool ARMConstantIslands::OptimizeThumb2Instructions(MachineFunction &MF) {
}
}
MadeChange |= OptimizeThumb2JumpTables(MF);
MadeChange |= OptimizeThumb2Branches(MF);
MadeChange |= OptimizeThumb2JumpTables(MF);
return MadeChange;
}
bool ARMConstantIslands::OptimizeThumb2Branches(MachineFunction &MF) {
return false;
bool MadeChange = false;
for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i) {
ImmBranch &Br = ImmBranches[i];
unsigned Opcode = Br.MI->getOpcode();
unsigned NewOpc = 0;
unsigned Scale = 1;
unsigned Bits = 0;
switch (Opcode) {
default: break;
case ARM::t2B:
NewOpc = ARM::tB;
Bits = 11;
Scale = 2;
break;
case ARM::t2Bcc:
NewOpc = ARM::tBcc;
Bits = 8;
Scale = 2;
break;
}
if (!NewOpc)
continue;
unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale;
MachineBasicBlock *DestBB = Br.MI->getOperand(0).getMBB();
if (BBIsInRange(Br.MI, DestBB, MaxOffs)) {
Br.MI->setDesc(TII->get(NewOpc));
MachineBasicBlock *MBB = Br.MI->getParent();
BBSizes[MBB->getNumber()] -= 2;
AdjustBBOffsetsAfter(MBB, -2);
++NumT2BrShrunk;
MadeChange = true;
}
}
return MadeChange;
}

9
llvm/lib/Target/ARM/ARMInstrThumb.td
View File

@ -250,7 +250,7 @@ let isBranch = 1, isTerminator = 1 in {
let isBarrier = 1 in {
let isPredicable = 1 in
def tB : T1I<(outs), (ins brtarget:$target), IIC_Br,
"b $target", [(br bb:$target)]>;
"b.n $target", [(br bb:$target)]>;
// Far jump
let Defs = [LR] in
@ -268,7 +268,7 @@ let isBranch = 1, isTerminator = 1 in {
// a two-value operand where a dag node expects two operands. :(
let isBranch = 1, isTerminator = 1 in
def tBcc : T1I<(outs), (ins brtarget:$target, pred:$cc), IIC_Br,
"b$cc $target",
"b$cc.n $target",
[/*(ARMbrcond bb:$target, imm:$cc)*/]>;
//===----------------------------------------------------------------------===//
@ -310,9 +310,10 @@ def tRestore : T1pIs<(outs tGPR:$dst), (ins t_addrmode_sp:$addr), IIC_iLoad,
"ldr", " $dst, $addr", []>;
// Load tconstpool
// FIXME: Added .n suffix to workaround a Darwin assembler bug.
let canFoldAsLoad = 1 in
def tLDRpci : T1pIs<(outs tGPR:$dst), (ins i32imm:$addr), IIC_iLoad,
"ldr", " $dst, $addr",
"ldr", ".n $dst, $addr",
[(set tGPR:$dst, (load (ARMWrapper tconstpool:$addr)))]>;
// Special LDR for loads from non-pc-relative constpools.
@ -628,7 +629,7 @@ def tMOVCCi : T1pIt<(outs GPR:$dst), (ins GPR:$lhs, i32imm:$rhs), IIC_iALU,
// tLEApcrel - Load a pc-relative address into a register without offending the
// assembler.
def tLEApcrel : T1I<(outs tGPR:$dst), (ins i32imm:$label, pred:$p), IIC_iALU,
"adr$p.n $dst, #$label", []>;
"adr$p $dst, #$label", []>;
def tLEApcrelJT : T1I<(outs tGPR:$dst),
(ins i32imm:$label, lane_cst:$id, pred:$p),

61
llvm/test/CodeGen/Thumb2/thumb2-branch.ll Normal file
View File

@ -0,0 +1,61 @@
; RUN: llvm-as < %s | llc -march=thumb -mattr=+thumb2 -disable-arm-if-conversion | FileCheck %s
define void @f1(i32 %a, i32 %b, i32* %v) {
entry:
; CHECK: f1:
; CHECK bne LBB
%tmp = icmp eq i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp, label %cond_true, label %return
cond_true: ; preds = %entry
store i32 0, i32* %v
ret void
return: ; preds = %entry
ret void
}
define void @f2(i32 %a, i32 %b, i32* %v) {
entry:
; CHECK: f2:
; CHECK bge LBB
%tmp = icmp slt i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp, label %cond_true, label %return
cond_true: ; preds = %entry
store i32 0, i32* %v
ret void
return: ; preds = %entry
ret void
}
define void @f3(i32 %a, i32 %b, i32* %v) {
entry:
; CHECK: f3:
; CHECK bhs LBB
%tmp = icmp ult i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp, label %cond_true, label %return
cond_true: ; preds = %entry
store i32 0, i32* %v
ret void
return: ; preds = %entry
ret void
}
define void @f4(i32 %a, i32 %b, i32* %v) {
entry:
; CHECK: f4:
; CHECK blo LBB
%tmp = icmp ult i32 %a, %b ; <i1> [#uses=1]
br i1 %tmp, label %return, label %cond_true
cond_true: ; preds = %entry
store i32 0, i32* %v
ret void
return: ; preds = %entry
ret void
}

22
llvm/test/CodeGen/Thumb2/tls2.ll
View File

@ -1,19 +1,29 @@
; RUN: llvm-as < %s | llc -mtriple=thumbv7-linux-gnueabi | \
; RUN: grep {i(gottpoff)}
; RUN: llvm-as < %s | llc -mtriple=thumbv7-linux-gnueabi | \
; RUN: grep {ldr r., \[pc, r.\]}
; RUN: llvm-as < %s | llc -mtriple=thumbv7-linux-gnueabi \
; RUN: -relocation-model=pic | grep {__tls_get_addr}
; RUN: llvm-as < %s | llc -mtriple=thumbv7-linux-gnueabi | FileCheck %s -check-prefix=CHECK-NOT-PIC
; RUN: llvm-as < %s | llc -mtriple=thumbv7-linux-gnueabi -relocation-model=pic | FileCheck %s -check-prefix=CHECK-PIC
@i = external thread_local global i32 ; <i32*> [#uses=2]
define i32 @f() {
entry:
; CHECK-NOT-PIC: f:
; CHECK-NOT-PIC: add r0, pc
; CHECK-NOT-PIC: ldr r1, [r0]
; CHECK-NOT-PIC: i(gottpoff)
; CHECK-PIC: f:
; CHECK-PIC: bl __tls_get_addr(PLT)
%tmp1 = load i32* @i ; <i32> [#uses=1]
ret i32 %tmp1
}
define i32* @g() {
entry:
; CHECK-NOT-PIC: g:
; CHECK-NOT-PIC: add r0, pc
; CHECK-NOT-PIC: ldr r1, [r0]
; CHECK-NOT-PIC: i(gottpoff)
; CHECK-PIC: g:
; CHECK-PIC: bl __tls_get_addr(PLT)
ret i32* @i
}