[llvm] r251498 - Revert r251492 "[IndVarSimplify] Rewrite loop exit values with their
Chen Li via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 27 22:15:51 PDT 2015
Author: chenli
Date: Wed Oct 28 00:15:51 2015
New Revision: 251498
URL: http://llvm.org/viewvc/llvm-project?rev=251498&view=rev
Log:
Revert r251492 "[IndVarSimplify] Rewrite loop exit values with their
initial values from loop preheader", because it broke some bots.
Removed:
llvm/trunk/test/Transforms/IndVarSimplify/rewrite-loop-exit-value.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp
llvm/trunk/test/Transforms/LoopUnroll/scevunroll.ll
Modified: llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp?rev=251498&r1=251497&r2=251498&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/IndVarSimplify.cpp Wed Oct 28 00:15:51 2015
@@ -132,7 +132,6 @@ private:
bool canLoopBeDeleted(Loop *L, SmallVector<RewritePhi, 8> &RewritePhiSet);
void rewriteLoopExitValues(Loop *L, SCEVExpander &Rewriter);
- void rewriteFirstIterationLoopExitValues(Loop *L);
Value *linearFunctionTestReplace(Loop *L, const SCEV *BackedgeTakenCount,
PHINode *IndVar, SCEVExpander &Rewriter);
@@ -701,71 +700,6 @@ void IndVarSimplify::rewriteLoopExitValu
Rewriter.clearInsertPoint();
}
-//===---------------------------------------------------------------------===//
-// rewriteFirstIterationLoopExitValues: Rewrite loop exit values if we know
-// they will exit at the first iteration.
-//===---------------------------------------------------------------------===//
-
-/// Check to see if this loop has loop invariant conditions which lead to loop
-/// exits. If so, we know that if the exit path is taken, it is at the first
-/// loop iteration. This lets us predict exit values of PHI nodes that live in
-/// loop header.
-void IndVarSimplify::rewriteFirstIterationLoopExitValues(Loop *L) {
- // Verify the input to the pass is already in LCSSA form.
- assert(L->isLCSSAForm(*DT));
-
- SmallVector<BasicBlock *, 8> ExitBlocks;
- L->getUniqueExitBlocks(ExitBlocks);
-
- for (auto *ExitBB : ExitBlocks) {
- BasicBlock::iterator begin = ExitBB->begin();
- // If there are no more PHI nodes in this exit block, then no more
- // values defined inside the loop are used on this path.
- while (auto *PN = dyn_cast<PHINode>(begin++)) {
- for (unsigned IncomingValIdx = 0, e = PN->getNumIncomingValues();
- IncomingValIdx != e; ++IncomingValIdx) {
- auto *IncomingBB = PN->getIncomingBlock(IncomingValIdx);
- if (!L->contains(IncomingBB))
- continue;
-
- // Get condition that leads to the exit path.
- auto *TermInst = IncomingBB->getTerminator();
-
- Value *Cond = nullptr;
- if (auto *BI = dyn_cast<BranchInst>(TermInst)) {
- // Must be a conditional branch, otherwise the block
- // should not be in the loop.
- Cond = BI->getCondition();
- } else if (auto *SI = dyn_cast<SwitchInst>(TermInst))
- Cond = SI->getCondition();
-
- // All non-instructions are loop-invariant.
- if (isa<Instruction>(Cond) && !L->isLoopInvariant(Cond))
- continue;
-
- auto *ExitVal =
- dyn_cast<PHINode>(PN->getIncomingValue(IncomingValIdx));
-
- // Only deal with PHIs.
- if (!ExitVal)
- continue;
-
- // If ExitVal is a PHI on the loop header, then we know its
- // value along this exit because the exit can only be taken
- // on the first iteration.
- auto *LoopPreheader = L->getLoopPreheader();
- assert(LoopPreheader && "Invalid loop");
- if (ExitVal->getBasicBlockIndex(LoopPreheader) != -1) {
- assert(ExitVal->getParent() == L->getHeader() &&
- "ExitVal must be in loop header");
- PN->setIncomingValue(IncomingValIdx,
- ExitVal->getIncomingValueForBlock(LoopPreheader));
- }
- }
- }
- }
-}
-
/// Check whether it is possible to delete the loop after rewriting exit
/// value. If it is possible, ignore ReplaceExitValue and do rewriting
/// aggressively.
@@ -2239,11 +2173,6 @@ bool IndVarSimplify::runOnLoop(Loop *L,
// loop may be sunk below the loop to reduce register pressure.
sinkUnusedInvariants(L);
- // rewriteFirstIterationLoopExitValues does not rely on the computation of
- // trip count and therefore can further simplify exit values in addition to
- // rewriteLoopExitValues.
- rewriteFirstIterationLoopExitValues(L);
-
// Clean up dead instructions.
Changed |= DeleteDeadPHIs(L->getHeader(), TLI);
// Check a post-condition.
Removed: llvm/trunk/test/Transforms/IndVarSimplify/rewrite-loop-exit-value.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/IndVarSimplify/rewrite-loop-exit-value.ll?rev=251497&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/IndVarSimplify/rewrite-loop-exit-value.ll (original)
+++ llvm/trunk/test/Transforms/IndVarSimplify/rewrite-loop-exit-value.ll (removed)
@@ -1,75 +0,0 @@
-; RUN: opt -indvars -instcombine -S < %s | FileCheck %s
-
-;; Test that loop's exit value is rewritten to its initial
-;; value from loop preheader
-define i32 @test1(i32* %var) {
-; CHECK-LABEL: @test1
-entry:
- %cond = icmp eq i32* %var, null
- br label %header
-
-header:
- %phi_indvar = phi i32 [0, %entry], [%indvar, %loop]
- br i1 %cond, label %loop, label %exit
-
-loop:
- %indvar = add i32 %phi_indvar, 1
- br label %header
-
-exit:
-; CHECK: ret i32 0
- ret i32 %phi_indvar
-}
-
-
-;; Test that inner loop's exit value is first rewritten to outer
-;; loop's induction variable, and then further rewritten to a
-;; constant when process outer loop.
-define i32 @test2(i32* %var1, i32* %var2) {
-; CHECK-LABEL: @test2
-entry:
- %cond1 = icmp eq i32* %var1, null
- %cond2 = icmp eq i32* %var2, null
- br label %outer_header
-
-outer_header:
- %phi_outer = phi i32 [0, %entry], [%indvar_outer, %inner_exit]
- br label %inner_header
-
-inner_header:
- %phi_inner = phi i32 [%phi_outer, %outer_header], [%indvar_inner, %loop]
- br i1 %cond1, label %loop, label %exit
-
-loop:
- %indvar_inner = add i32 %phi_inner, 1
- br i1 %cond2, label %inner_header, label %inner_exit
-
-inner_exit:
- %indvar_outer = add i32 %phi_outer, 1
- br label %outer_header
-
-exit:
-;; %phi_inner is first rewritten to %phi_outer
-;; and then %phi_outer is rewritten to 0
- %ret_val = add i32 %phi_inner, %phi_outer
-; CHECK: ret i32 0
- ret i32 %ret_val
-}
-
-;; Test that we can not rewrite loop exit value if it's not
-;; a phi node (%indvar is an add instruction in this test).
-define i32 @test3(i32* %var) {
-; CHECK-LABEL: @test3
-entry:
- %cond = icmp eq i32* %var, null
- br label %header
-
-header:
- %phi_indvar = phi i32 [0, %entry], [%indvar, %header]
- %indvar = add i32 %phi_indvar, 1
- br i1 %cond, label %header, label %exit
-
-exit:
-; CHECK: ret i32 %indvar
- ret i32 %indvar
-}
\ No newline at end of file
Modified: llvm/trunk/test/Transforms/LoopUnroll/scevunroll.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/scevunroll.ll?rev=251498&r1=251497&r2=251498&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/scevunroll.ll (original)
+++ llvm/trunk/test/Transforms/LoopUnroll/scevunroll.ll Wed Oct 28 00:15:51 2015
@@ -184,7 +184,7 @@ for.body87:
; CHECK: for.body:
; CHECK: %b.03 = phi i32 [ 0, %entry ], [ %add, %for.cond ]
; CHECK: return:
-; CHECK: %b.03.lcssa = phi i32 [ %b.03, %for.body ], [ 0, %for.cond ]
+; CHECK: %b.03.lcssa = phi i32 [ %b.03, %for.body ], [ %b.03, %for.cond ]
define void @nsw_latch(i32* %a) nounwind {
entry:
br label %for.body
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