From e3e394d982a2bd2bc37edb1f8c3492d0382e37a9 Mon Sep 17 00:00:00 2001 From: Bill Wendling Date: Sun, 4 Mar 2012 10:46:01 +0000 Subject: [PATCH] Do trivial CSE of dead BBs during codegen preparation. Some BBs can become dead after codegen preparation. If we delete them here, it could help enable tail-call optimizations later on. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152002 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/CodeGenPrepare.cpp | 21 ++++++++++++++++++- .../CodeGen/ARM/2011-03-15-LdStMultipleBug.ll | 2 +- test/CodeGen/ARM/cse-libcalls.ll | 4 ++-- test/CodeGen/X86/2011-11-09-FoldImpDefs.ll | 2 +- .../X86/unreachable-stack-protector.ll | 2 +- 5 files changed, 25 insertions(+), 6 deletions(-) diff --git a/lib/Transforms/Scalar/CodeGenPrepare.cpp b/lib/Transforms/Scalar/CodeGenPrepare.cpp index 5ca5e47cd05..aad3a924f14 100644 --- a/lib/Transforms/Scalar/CodeGenPrepare.cpp +++ b/lib/Transforms/Scalar/CodeGenPrepare.cpp @@ -65,6 +65,11 @@ static cl::opt DisableBranchOpts( "disable-cgp-branch-opts", cl::Hidden, cl::init(false), cl::desc("Disable branch optimizations in CodeGenPrepare")); +// FIXME: Remove this abomination once all of the tests pass without it! +static cl::opt DisableDeleteDeadBlocks( + "disable-cgp-delete-dead-blocks", cl::Hidden, cl::init(false), + cl::desc("Disable deleting dead blocks in CodeGenPrepare")); + namespace { class CodeGenPrepare : public FunctionPass { /// TLI - Keep a pointer of a TargetLowering to consult for determining @@ -160,8 +165,22 @@ bool CodeGenPrepare::runOnFunction(Function &F) { if (!DisableBranchOpts) { MadeChange = false; - for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) + SmallPtrSet WorkList; + for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) { + SmallVector Successors(succ_begin(BB), succ_end(BB)); MadeChange |= ConstantFoldTerminator(BB, true); + if (!MadeChange) continue; + + for (SmallVectorImpl::iterator + II = Successors.begin(), IE = Successors.end(); II != IE; ++II) + if (pred_begin(*II) == pred_end(*II)) + WorkList.insert(*II); + } + + if (!DisableDeleteDeadBlocks) + for (SmallPtrSet::iterator + I = WorkList.begin(), E = WorkList.end(); I != E; ++I) + DeleteDeadBlock(*I); if (MadeChange) ModifiedDT = true; diff --git a/test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll b/test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll index ccda281e901..2faa04af8ba 100644 --- a/test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll +++ b/test/CodeGen/ARM/2011-03-15-LdStMultipleBug.ll @@ -1,4 +1,4 @@ -; RUN: llc < %s -mtriple=thumbv7-apple-darwin10 -relocation-model=pic -disable-fp-elim -mcpu=cortex-a8 | FileCheck %s +; RUN: llc < %s -mtriple=thumbv7-apple-darwin10 -relocation-model=pic -disable-fp-elim -disable-cgp-delete-dead-blocks -mcpu=cortex-a8 | FileCheck %s ; Do not form Thumb2 ldrd / strd if the offset is not multiple of 4. ; rdar://9133587 diff --git a/test/CodeGen/ARM/cse-libcalls.ll b/test/CodeGen/ARM/cse-libcalls.ll index 0dcf9ddc0bb..1d011be93c3 100644 --- a/test/CodeGen/ARM/cse-libcalls.ll +++ b/test/CodeGen/ARM/cse-libcalls.ll @@ -4,7 +4,7 @@ target triple = "i386-apple-darwin8" ; Without CSE of libcalls, there are two calls in the output instead of one. -define i32 @u_f_nonbon(double %lambda) nounwind { +define double @u_f_nonbon(double %lambda) nounwind { entry: %tmp19.i.i = load double* null, align 4 ; [#uses=2] %tmp6.i = fcmp olt double %tmp19.i.i, 1.000000e+00 ; [#uses=1] @@ -26,5 +26,5 @@ bb502.loopexit.i: ; preds = %bb28.i br i1 false, label %bb.nph53.i, label %bb508.i bb508.i: ; preds = %bb502.loopexit.i, %entry - ret i32 1 + ret double %tmp10.i4 } diff --git a/test/CodeGen/X86/2011-11-09-FoldImpDefs.ll b/test/CodeGen/X86/2011-11-09-FoldImpDefs.ll index 095d8c68c22..029aa91658d 100644 --- a/test/CodeGen/X86/2011-11-09-FoldImpDefs.ll +++ b/test/CodeGen/X86/2011-11-09-FoldImpDefs.ll @@ -1,4 +1,4 @@ -; RUN: llc < %s -verify-regalloc | FileCheck %s +; RUN: llc < %s -disable-cgp-delete-dead-blocks -verify-regalloc | FileCheck %s ; PR11347 ; ; This test case materializes the constant 1 in a register: diff --git a/test/CodeGen/X86/unreachable-stack-protector.ll b/test/CodeGen/X86/unreachable-stack-protector.ll index eeebceea71d..b066297ff1b 100644 --- a/test/CodeGen/X86/unreachable-stack-protector.ll +++ b/test/CodeGen/X86/unreachable-stack-protector.ll @@ -1,4 +1,4 @@ -; RUN: llc < %s | FileCheck %s +; RUN: llc < %s -disable-cgp-delete-dead-blocks | 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-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64" target triple = "x86_64-apple-darwin10.0.0"