================
@@ -2608,6 +2612,21 @@ void
WebAssemblyCFGStackify::rewriteDepthImmediates(MachineFunction &MF) {
Stack.push_back(std::make_pair(&MBB, &MI));
break;
+ case WebAssembly::BR_IF: {
+ // this is the last place where we can easily calculate the branch
+ // probabilities. we do not emit scf-ifs, therefore, only br_ifs have
+ // to be annotated with branch probabilities.
+ if (MF.getSubtarget<WebAssemblySubtarget>().hasBranchHinting() &&
+ MI.getParent()->hasSuccessorProbabilities()) {
+ const auto Prob = MBPI->getEdgeProbability(
+ MI.getParent(), MI.operands().begin()->getMBB());
+ WebAssemblyFunctionInfo *MFI = MF.getInfo<WebAssemblyFunctionInfo>();
+ assert(!MFI->BranchProbabilities.contains(&MI));
+ MFI->BranchProbabilities[&MI] = Prob;
+ }
----------------
Lukasdoe wrote:
Update: The changes in the `CFGGraphStackify` pass are now completely reverted.
Branch hints are only generated based on `br_if` instructions encountered
during ASM printing, mostly based on @kripken 's earlier contribution. This
change significantly reduces the memory overhead (and probably runtime
overhead), since we do not store branch hints for branches that are removed by
passes after `CFGStackify`.
https://github.com/llvm/llvm-project/pull/146230
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