[cfe-commits] r129652 - in /cfe/trunk: lib/CodeGen/CGCleanup.cpp lib/CodeGen/CGStmt.cpp lib/CodeGen/CodeGenFunction.h test/CodeGen/switch-dce.c

[John McCall]

On Apr 16, 2011, at 5:54 PM, Chris Lattner wrote:
> Author: lattner
> Date: Sat Apr 16 19:54:30 2011
> New Revision: 129652
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=129652&view=rev
> Log:
> implement rdar://9289524 - case followed immediately by break results in empty IR block,
> a -O0 code quality issue.

Awesome, thanks!

> +  // If the body of the case is just a 'break', try to not emit an empty block.
> +  if (isa<BreakStmt>(S.getSubStmt())) {
> +    JumpDest Block = BreakContinueStack.back().BreakBlock;
> +    
> +    // Only do this optimization if there are no cleanups that need emitting.
> +    if (isObviouslyBranchWithoutCleanups(Block)) {
> +      llvm::APSInt CaseVal = S.getLHS()->EvaluateAsInt(getContext());

This is common between these two code paths and would be nice to hoist.

John.