[llvm-commits] [llvm] r130528 - in /llvm/trunk: lib/Transforms/Utils/SimplifyCFG.cpp test/Transforms/SimplifyCFG/PhiEliminate3.ll

[Chris Lattner]

On Apr 29, 2011, at 11:47 AM, Peter Collingbourne wrote:
> Author: pcc
> Date: Fri Apr 29 13:47:38 2011
> New Revision: 130528
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=130528&view=rev
> Log:
> SimplifyCFG: Expose phi node folding cost threshold as command line parameter

Hi Peter,

Why?

-Chris

> 
> Added:
>    llvm/trunk/test/Transforms/SimplifyCFG/PhiEliminate3.ll
> Modified:
>    llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
> 
> Modified: llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp?rev=130528&r1=130527&r2=130528&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp (original)
> +++ llvm/trunk/lib/Transforms/Utils/SimplifyCFG.cpp Fri Apr 29 13:47:38 2011
> @@ -37,6 +37,10 @@
> #include <map>
> using namespace llvm;
> 
> +static cl::opt<unsigned>
> +PHINodeFoldingThreshold("phi-node-folding-threshold", cl::Hidden, cl::init(1),
> +   cl::desc("Control the amount of phi node folding to perform (default = 1)"));
> +
> static cl::opt<bool>
> DupRet("simplifycfg-dup-ret", cl::Hidden, cl::init(false),
>        cl::desc("Duplicate return instructions into unconditional branches"));
> @@ -1246,7 +1250,8 @@
>   // instructions.  While we are at it, keep track of the instructions
>   // that need to be moved to the dominating block.
>   SmallPtrSet<Instruction*, 4> AggressiveInsts;
> -  unsigned MaxCostVal0 = 1, MaxCostVal1 = 1;
> +  unsigned MaxCostVal0 = PHINodeFoldingThreshold,
> +           MaxCostVal1 = PHINodeFoldingThreshold;
> 
>   for (BasicBlock::iterator II = BB->begin(); isa<PHINode>(II);) {
>     PHINode *PN = cast<PHINode>(II++);
> 
> Added: llvm/trunk/test/Transforms/SimplifyCFG/PhiEliminate3.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/SimplifyCFG/PhiEliminate3.ll?rev=130528&view=auto
> ==============================================================================
> --- llvm/trunk/test/Transforms/SimplifyCFG/PhiEliminate3.ll (added)
> +++ llvm/trunk/test/Transforms/SimplifyCFG/PhiEliminate3.ll Fri Apr 29 13:47:38 2011
> @@ -0,0 +1,34 @@
> +; Test merging of blocks containing complex expressions,
> +; with various folding thresholds
> +;
> +; RUN: opt < %s -simplifycfg -S -phi-node-folding-threshold=1 | grep N:
> +; RUN: opt < %s -simplifycfg -S -phi-node-folding-threshold=2 | not grep N:
> +; RUN: opt < %s -simplifycfg -S -phi-node-folding-threshold=2 | grep M:
> +; RUN: opt < %s -simplifycfg -S -phi-node-folding-threshold=7 | not grep M:
> +;
> +
> +define i32 @test(i1 %a, i1 %b, i32 %i, i32 %j, i32 %k) {
> +entry:
> +        br i1 %a, label %M, label %O
> +O:
> +        br i1 %b, label %P, label %Q
> +P:
> +        %iaj = add i32 %i, %j
> +        %iajak = add i32 %iaj, %k
> +        br label %N
> +Q:
> +        %ixj = xor i32 %i, %j
> +        %ixjxk = xor i32 %ixj, %k
> +        br label %N
> +N:
> +        ; This phi should be foldable if threshold >= 2
> +        %Wp = phi i32 [ %iajak, %P ], [ %ixjxk, %Q ]
> +        %Wp2 = add i32 %Wp, %Wp
> +        br label %M
> +M:
> +        ; This phi should be foldable if threshold >= 7
> +        %W = phi i32 [ %Wp2, %N ], [ 2, %entry ]
> +        %R = add i32 %W, 1
> +        ret i32 %R
> +}
> +
> 
> 
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits