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Cleanup initial-value constants in PPCCTRLoops

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Because the initial-value constants had not been added to the list
of instructions considered for DCE the resulting code had redundant
constant-materialization instructions.

llvm-svn: 177294
This commit is contained in:
Hal Finkel 2013-03-18 17:40:27 +00:00
parent edb8448b25
commit 2ab64cdbb2
2 changed files with 34 additions and 2 deletions
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11
lib/Target/PowerPC/PPCCTRLoops.cpp
View File

@ -380,13 +380,13 @@ CountValue *PPCCTRLoops::getTripCount(MachineLoop *L,
assert(InitialValue->isReg() && "Expecting register for init value");
unsigned InitialValueReg = InitialValue->getReg();
const MachineInstr *DefInstr = MRI->getVRegDef(InitialValueReg);
MachineInstr *DefInstr = MRI->getVRegDef(InitialValueReg);
// Here we need to look for an immediate load (an li or lis/ori pair).
if (DefInstr && (DefInstr->getOpcode() == PPC::ORI8 ||
DefInstr->getOpcode() == PPC::ORI)) {
int64_t start = (short) DefInstr->getOperand(2).getImm();
const MachineInstr *DefInstr2 =
MachineInstr *DefInstr2 =
MRI->getVRegDef(DefInstr->getOperand(0).getReg());
if (DefInstr2 && (DefInstr2->getOpcode() == PPC::LIS8 ||
DefInstr2->getOpcode() == PPC::LIS)) {
@ -399,6 +399,10 @@ CountValue *PPCCTRLoops::getTripCount(MachineLoop *L,
if ((count % iv_value) != 0) {
return 0;
}
OldInsts.push_back(DefInstr);
OldInsts.push_back(DefInstr2);
return new CountValue(count/iv_value);
}
} else if (DefInstr && (DefInstr->getOpcode() == PPC::LI8 ||
@ -409,6 +413,9 @@ CountValue *PPCCTRLoops::getTripCount(MachineLoop *L,
if ((count % iv_value) != 0) {
return 0;
}
OldInsts.push_back(DefInstr);
return new CountValue(count/iv_value);
} else if (iv_value == 1 || iv_value == -1) {
// We can't determine a constant starting value.

25
test/CodeGen/PowerPC/ctr-cleanup.ll Normal file
View File

@ -0,0 +1,25 @@
; RUN: llc < %s -mcpu=a2 | FileCheck %s
target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64"
target triple = "powerpc64-unknown-linux-gnu"
define void @main() #0 {
entry:
br i1 undef, label %for.end, label %for.body
for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 1, %entry ]
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp eq i32 %lftr.wideiv, 5
br i1 %exitcond, label %for.end, label %for.body
; CHECK: @main
; CHECK: li {{[0-9]+}}, 4
; CHECK-NOT: li {{[0-9]+}}, 4
; CHECK: bdnz
for.end: ; preds = %for.body, %entry
ret void
}
attributes #0 = { nounwind "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }