6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-02-16 00:33:10 +00:00
Code Issues Projects Releases Wiki Activity

Fix a nasty bug that caused us to unroll EXTREMELY large loops due to overflow

Browse Source 
in the size calculation.

This is not something you want to see:
Loop Unroll: F[main] Loop %no_exit Loop Size = 2 Trip Count = 2147483648 - UNROLLING!

The problem was that 2*2147483648 == 0.

Now we get:
Loop Unroll: F[main] Loop %no_exit Loop Size = 2 Trip Count = 2147483648 - TOO LARGE: 4294967296>100

Thanks to some anonymous person playing with the demo page that repeatedly
caused zion to go into swapping land.  That's one way to ensure you'll get
a quick bugfix.  :)

Testcase here: Transforms/LoopUnroll/2004-05-13-DontUnrollTooMuch.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13564 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-05-13 20:43:31 +00:00
parent 488b72bd7f
commit 82fec4e31d
2 changed files with 10 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -1475,6 +1475,13 @@ Instruction *InstCombiner::visitSetCondInst(BinaryOperator &I) {
// integers at the end of their ranges...
//
if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
if (Instruction *LHSI = dyn_cast<Instruction>(Op0))
if (LHSI->getOpcode() == Instruction::Div && LHSI->hasOneUse() &&
isa<ConstantInt>(LHSI->getOperand(1))) {
std::cerr << "COULD FOLD: " << *LHSI;
std::cerr << "COULD FOLD: " << I << "\n";
}
// Simplify seteq and setne instructions...
if (I.getOpcode() == Instruction::SetEQ ||
I.getOpcode() == Instruction::SetNE) {

6
lib/Transforms/Scalar/LoopUnroll.cpp
View File

@ -139,9 +139,9 @@ bool LoopUnroll::visitLoop(Loop *L) {
DEBUG(std::cerr << "Loop Unroll: F[" << BB->getParent()->getName()
<< "] Loop %" << BB->getName() << " Loop Size = " << LoopSize
<< " Trip Count = " << TripCount << " - ");
if (LoopSize*TripCount > UnrollThreshold) {
DEBUG(std::cerr << "TOO LARGE: " << LoopSize*TripCount << ">"
<< UnrollThreshold << "\n");
uint64_t Size = (uint64_t)LoopSize*(uint64_t)TripCount;
if (Size > UnrollThreshold) {
DEBUG(std::cerr << "TOO LARGE: " << Size << ">" << UnrollThreshold << "\n");
return Changed;
}
DEBUG(std::cerr << "UNROLLING!\n");