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Only use instructions as insert locations for SCEVExpander 

SCEVExpander, which we are using during code generation, only allows
instructions as insert locations, but breaks in case BasicBlock->end() iterators
are passed to it due to it trying to obtain the basic block in which code should
be generated by calling Instruction->getParent(), which is not defined for
->end() iterators.

This change adds an assert to Polly that ensures we only pass valid instructions
to SCEVExpander and it fixes one case, where we used IRBuilder->SetInsertBlock()
to set an ->end() insert location which was later passed to SCEVExpander.

In general, Polly is always trying to build up the CFG first, before we actually
insert instructions into the CFG sceleton. As a result, each basic block should
already have at least one branch instruction before we start adding code. Hence,
always requiring the IRBuilder insert location to be set to a real instruction
should always be possible.

Thanks Utpal Bora <cs14mtech11017@iith.ac.in> for his help with test case
reduction.

llvm-svn: 243830
This commit is contained in:
Tobias Grosser 2015-08-01 09:07:57 +00:00
parent d3f21833b9
commit 45e7944bcf
2 changed files with 57 additions and 1 deletions
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4
polly/lib/CodeGen/BlockGenerators.cpp
View File

@ -123,6 +123,8 @@ Value *BlockGenerator::getNewValue(ScopStmt &Stmt, const Value *Old,
->getParent()
->getDataLayout(),
"polly");
assert(Builder.GetInsertPoint() != Builder.GetInsertBlock()->end() &&
"Only instructions can be insert points for SCEVExpander");
Value *Expanded = Expander.expandCodeFor(NewScev, Old->getType(),
Builder.GetInsertPoint());
@ -1056,7 +1058,7 @@ void RegionGenerator::copyStmt(ScopStmt &Stmt, ValueMapT &GlobalMap,
ValueMapT &RegionMap = RegionMaps[BBCopy];
RegionMap.insert(BlockMap.begin(), BlockMap.end());
Builder.SetInsertPoint(BBCopy);
Builder.SetInsertPoint(BICopy);
copyInstScalar(Stmt, BI, RegionMap, GlobalMap, LTS);
BICopy->eraseFromParent();
}

54
polly/test/Isl/CodeGen/non-affine-phi-node-expansion.ll Normal file
View File

@ -0,0 +1,54 @@
; RUN: opt %loadPolly -polly-codegen -S < %s | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
%struct.wombat = type {[4 x i32]}
; CHECK: polly.stmt.bb3.entry: ; preds = %polly.start
; CHECK: br label %polly.stmt.bb3
; CHECK: polly.stmt.bb3: ; preds = %polly.stmt.bb3.entry
; CHECK: %polly.subregion.iv = phi i32 [ 0, %polly.stmt.bb3.entry ]
; CHECK: %polly.subregion.iv.inc = add i32 %polly.subregion.iv, 1
; CHECK: br i1 true, label %polly.stmt.bb4, label %polly.stmt.bb5
; CHECK: polly.stmt.bb4: ; preds = %polly.stmt.bb3
; CHECK: br label %polly.stmt.bb13.exit
; CHECK: polly.stmt.bb5: ; preds = %polly.stmt.bb3
; CHECK: %tmp7_p_scalar_ = load i32, i32* %B, !alias.scope !0, !noalias !2
; CHECK: store i32 %tmp7_p_scalar_, i32* %polly.access.cast.arg1, !alias.scope !3, !noalias !4
; CHECK: br label %polly.stmt.bb13.exit
; Function Attrs: nounwind uwtable
define void @quux(%struct.wombat* %arg, i32* %B) {
bb:
br i1 undef, label %bb2, label %bb1
bb1: ; preds = %bb
br label %bb2
bb2: ; preds = %bb1, %bb
%tmp = phi i1 [ true, %bb ], [ undef, %bb1 ]
br label %bb3
bb3: ; preds = %bb13, %bb2
br i1 %tmp, label %bb4, label %bb5
bb4: ; preds = %bb3
br label %bb13
bb5: ; preds = %bb3
%tmp7 = load i32, i32* %B
%tmp12 = getelementptr inbounds %struct.wombat, %struct.wombat* %arg, i64 0, i32 0, i64 0
store i32 %tmp7, i32* %tmp12
br label %bb13
bb13: ; preds = %bb5, %bb4
br i1 false, label %bb3, label %bb14
bb14: ; preds = %bb13
br label %bb15
bb15: ; preds = %bb14
unreachable
}