[llvm-commits] [llvm] r129914 - in /llvm/trunk: include/llvm/CodeGen/SelectionDAGISel.h lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp test/CodeGen/X86/fast-isel-x86-64.ll
Daniel Dunbar
daniel at zuster.org
Thu Apr 21 09:14:47 PDT 2011
Author: ddunbar
Date: Thu Apr 21 11:14:46 2011
New Revision: 129914
URL: http://llvm.org/viewvc/llvm-project?rev=129914&view=rev
Log:
Revert r1296656, "Fix rdar://9289512 - not folding load into compare at -O0...",
which broke a couple GCC test suite tests at -O0.
Modified:
llvm/trunk/include/llvm/CodeGen/SelectionDAGISel.h
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
llvm/trunk/test/CodeGen/X86/fast-isel-x86-64.ll
Modified: llvm/trunk/include/llvm/CodeGen/SelectionDAGISel.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/SelectionDAGISel.h?rev=129914&r1=129913&r2=129914&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/SelectionDAGISel.h (original)
+++ llvm/trunk/include/llvm/CodeGen/SelectionDAGISel.h Thu Apr 21 11:14:46 2011
@@ -280,8 +280,7 @@
void PrepareEHLandingPad();
void SelectAllBasicBlocks(const Function &Fn);
- bool TryToFoldFastISelLoad(const LoadInst *LI, const Instruction *FoldInst,
- FastISel *FastIS);
+ bool TryToFoldFastISelLoad(const LoadInst *LI, FastISel *FastIS);
void FinishBasicBlock();
void SelectBasicBlock(BasicBlock::const_iterator Begin,
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp?rev=129914&r1=129913&r2=129914&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp Thu Apr 21 11:14:46 2011
@@ -746,31 +746,9 @@
-/// TryToFoldFastISelLoad - We're checking to see if we can fold the specified
-/// load into the specified FoldInst. Note that we could have a sequence where
-/// multiple LLVM IR instructions are folded into the same machineinstr. For
-/// example we could have:
-/// A: x = load i32 *P
-/// B: y = icmp A, 42
-/// C: br y, ...
-///
-/// In this scenario, LI is "A", and FoldInst is "C". We know about "B" (and
-/// any other folded instructions) because it is between A and C.
-///
-/// If we succeed in folding the load into the operation, return true.
-///
+
bool SelectionDAGISel::TryToFoldFastISelLoad(const LoadInst *LI,
- const Instruction *FoldInst,
FastISel *FastIS) {
- SmallPtrSet<const Instruction*, 4> FoldedInsts;
- for (BasicBlock::const_iterator II = FoldInst; &*II != LI; --II)
- FoldedInsts.insert(II);
-
- // We know that the load has a single use, but don't know what it is. If it
- // isn't one of the folded instructions, then we can't succeed here.
- if (!FoldedInsts.count(LI->use_back()))
- return false;
-
// Don't try to fold volatile loads. Target has to deal with alignment
// constraints.
if (LI->isVolatile()) return false;
@@ -855,10 +833,10 @@
/// Return false if it needs to be emitted.
static bool isFoldedOrDeadInstruction(const Instruction *I,
FunctionLoweringInfo *FuncInfo) {
- return !I->mayWriteToMemory() && // Side-effecting instructions aren't folded.
- !isa<TerminatorInst>(I) && // Terminators aren't folded.
- !isa<DbgInfoIntrinsic>(I) && // Debug instructions aren't folded.
- !FuncInfo->isExportedInst(I); // Exported instrs must be computed.
+ return !I->mayWriteToMemory() &&
+ !isa<TerminatorInst>(I) &&
+ !isa<DbgInfoIntrinsic>(I) &&
+ !FuncInfo->isExportedInst(I);
}
void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
@@ -950,20 +928,16 @@
// Try to select the instruction with FastISel.
if (FastIS->SelectInstruction(Inst)) {
- // If fast isel succeeded, skip over all the folded instructions, and
- // then see if there is a load right before the selected instructions.
- // Try to fold the load if so.
- const Instruction *BeforeInst = Inst;
- while (BeforeInst != Begin) {
- BeforeInst = llvm::prior(BasicBlock::const_iterator(BeforeInst));
- if (!isFoldedOrDeadInstruction(BeforeInst, FuncInfo))
- break;
- }
- if (BeforeInst != Inst && isa<LoadInst>(BeforeInst) &&
- BeforeInst->hasOneUse() &&
- TryToFoldFastISelLoad(cast<LoadInst>(BeforeInst), Inst, FastIS))
- // If we succeeded, don't re-select the load.
- BI = llvm::next(BasicBlock::const_iterator(BeforeInst));
+ // If fast isel succeeded, check to see if there is a single-use
+ // non-volatile load right before the selected instruction, and see if
+ // the load is used by the instruction. If so, try to fold it.
+ const Instruction *BeforeInst = 0;
+ if (Inst != Begin)
+ BeforeInst = llvm::prior(llvm::prior(BI));
+ if (BeforeInst && isa<LoadInst>(BeforeInst) &&
+ BeforeInst->hasOneUse() && *BeforeInst->use_begin() == Inst &&
+ TryToFoldFastISelLoad(cast<LoadInst>(BeforeInst), FastIS))
+ --BI; // If we succeeded, don't re-select the load.
continue;
}
Modified: llvm/trunk/test/CodeGen/X86/fast-isel-x86-64.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/fast-isel-x86-64.ll?rev=129914&r1=129913&r2=129914&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/fast-isel-x86-64.ll (original)
+++ llvm/trunk/test/CodeGen/X86/fast-isel-x86-64.ll Thu Apr 21 11:14:46 2011
@@ -14,28 +14,6 @@
; CHECK: andl $8,
-; rdar://9289512 - The load should fold into the compare.
-define void @test2(i64 %x) nounwind ssp {
-entry:
- %x.addr = alloca i64, align 8
- store i64 %x, i64* %x.addr, align 8
- %tmp = load i64* %x.addr, align 8
- %cmp = icmp sgt i64 %tmp, 42
- br i1 %cmp, label %if.then, label %if.end
-
-if.then: ; preds = %entry
- br label %if.end
-
-if.end: ; preds = %if.then, %entry
- ret void
-; CHECK: test2:
-; CHECK: movq %rdi, -8(%rsp)
-; CHECK: cmpq $42, -8(%rsp)
-}
-
-
-
-
@G = external global i32
define i64 @test3() nounwind {
%A = ptrtoint i32* @G to i64
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