[llvm] r362056 - [LV] Inform about exactly reason of loop illegality
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Wed May 29 22:03:12 PDT 2019
Author: fhahn
Date: Wed May 29 22:03:12 2019
New Revision: 362056
URL: http://llvm.org/viewvc/llvm-project?rev=362056&view=rev
Log:
[LV] Inform about exactly reason of loop illegality
Currently, only the following information is provided by LoopVectorizer
in the case when the CF of the loop is not legal for vectorization:
LV: Can't vectorize the instructions or CFG
LV: Not vectorizing: Cannot prove legality.
But this information is not enough for the root cause analysis; what is
exactly wrong with the loop should also be printed:
LV: Not vectorizing: The exiting block is not the loop latch.
Patch by Pavel Samolysov.
Reviewers: mkuper, hsaito, rengolin, fhahn
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D62311
Added:
llvm/trunk/test/Transforms/LoopVectorize/loop-legality-checks.ll
Removed:
llvm/trunk/test/Transforms/LoopVectorize/legal_preheader_check.ll
Modified:
llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
Modified: llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp?rev=362056&r1=362055&r2=362056&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp (original)
+++ llvm/trunk/lib/Transforms/Vectorize/LoopVectorizationLegality.cpp Wed May 29 22:03:12 2019
@@ -599,9 +599,10 @@ bool LoopVectorizationLegality::canVecto
// Check that this PHI type is allowed.
if (!PhiTy->isIntegerTy() && !PhiTy->isFloatingPointTy() &&
!PhiTy->isPointerTy()) {
+ LLVM_DEBUG(dbgs()
+ << "LV: Not vectorizing: Found a non-int non-pointer PHI.\n");
ORE->emit(createMissedAnalysis("CFGNotUnderstood", Phi)
<< "loop control flow is not understood by vectorizer");
- LLVM_DEBUG(dbgs() << "LV: Found an non-int non-pointer PHI.\n");
return false;
}
@@ -967,7 +968,8 @@ bool LoopVectorizationLegality::canVecto
// We must have a loop in canonical form. Loops with indirectbr in them cannot
// be canonicalized.
if (!Lp->getLoopPreheader()) {
- LLVM_DEBUG(dbgs() << "LV: Loop doesn't have a legal pre-header.\n");
+ LLVM_DEBUG(dbgs()
+ << "LV: Not vectorizing: Loop doesn't have a legal pre-header.\n");
ORE->emit(createMissedAnalysis("CFGNotUnderstood")
<< "loop control flow is not understood by vectorizer");
if (DoExtraAnalysis)
@@ -978,6 +980,8 @@ bool LoopVectorizationLegality::canVecto
// We must have a single backedge.
if (Lp->getNumBackEdges() != 1) {
+ LLVM_DEBUG(dbgs()
+ << "LV: Not vectorizing: The loop must have a single backedge.\n");
ORE->emit(createMissedAnalysis("CFGNotUnderstood")
<< "loop control flow is not understood by vectorizer");
if (DoExtraAnalysis)
@@ -988,6 +992,8 @@ bool LoopVectorizationLegality::canVecto
// We must have a single exiting block.
if (!Lp->getExitingBlock()) {
+ LLVM_DEBUG(dbgs()
+ << "LV: Not vectorizing: The loop must have an exiting block.\n");
ORE->emit(createMissedAnalysis("CFGNotUnderstood")
<< "loop control flow is not understood by vectorizer");
if (DoExtraAnalysis)
@@ -1000,6 +1006,8 @@ bool LoopVectorizationLegality::canVecto
// checked at the end of each iteration. With that we can assume that all
// instructions in the loop are executed the same number of times.
if (Lp->getExitingBlock() != Lp->getLoopLatch()) {
+ LLVM_DEBUG(dbgs()
+ << "LV: Not vectorizing: The exiting block is not the loop latch.\n");
ORE->emit(createMissedAnalysis("CFGNotUnderstood")
<< "loop control flow is not understood by vectorizer");
if (DoExtraAnalysis)
Removed: llvm/trunk/test/Transforms/LoopVectorize/legal_preheader_check.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/legal_preheader_check.ll?rev=362055&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/legal_preheader_check.ll (original)
+++ llvm/trunk/test/Transforms/LoopVectorize/legal_preheader_check.ll (removed)
@@ -1,27 +0,0 @@
-; RUN: opt < %s -loop-vectorize -debug -S -o /dev/null 2>&1 | FileCheck %s
-; REQUIRES: asserts
-
-; D40973
-; Make sure LV legal bails out when the loop doesn't have a legal pre-header.
-
-; CHECK: LV: Loop doesn't have a legal pre-header.
-
-define void @inc(i32 %n, i8* %P) {
- %1 = icmp sgt i32 %n, 0
- br i1 %1, label %BB1, label %BB2
-
-BB1:
- indirectbr i8* %P, [label %.lr.ph]
-
-BB2:
- br label %.lr.ph
-
-.lr.ph:
- %indvars.iv = phi i32 [ %indvars.iv.next, %.lr.ph ], [ 0, %BB1 ], [ 0, %BB2 ]
- %indvars.iv.next = add i32 %indvars.iv, 1
- %exitcond = icmp eq i32 %indvars.iv.next, %n
- br i1 %exitcond, label %._crit_edge, label %.lr.ph
-
-._crit_edge:
- ret void
-}
Added: llvm/trunk/test/Transforms/LoopVectorize/loop-legality-checks.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopVectorize/loop-legality-checks.ll?rev=362056&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopVectorize/loop-legality-checks.ll (added)
+++ llvm/trunk/test/Transforms/LoopVectorize/loop-legality-checks.ll Wed May 29 22:03:12 2019
@@ -0,0 +1,82 @@
+; RUN: opt < %s -loop-vectorize -debug-only=loop-vectorize -S -disable-output 2>&1 | FileCheck %s
+; REQUIRES: asserts
+
+; Make sure LV legal bails out when the exiting block != loop latch.
+; CHECK-LABEL: "latch_is_not_exiting"
+; CHECK: LV: Not vectorizing: The exiting block is not the loop latch.
+define i32 @latch_is_not_exiting() {
+entry:
+ br label %for.body
+
+for.body:
+ %i.02 = phi i32 [ 0, %entry ], [ %inc, %for.body ], [%inc, %for.second]
+ %inc = add nsw i32 %i.02, 1
+ %cmp = icmp slt i32 %inc, 16
+ br i1 %cmp, label %for.body, label %for.second
+
+for.second:
+ %cmps = icmp sgt i32 %inc, 16
+ br i1 %cmps, label %for.body, label %for.end
+
+for.end:
+ ret i32 0
+}
+
+; Make sure LV legal bails out when there is no exiting block
+; CHECK-LABEL: "no_exiting_block"
+; CHECK: LV: Not vectorizing: The loop must have an exiting block.
+define i32 @no_exiting_block() {
+entry:
+ br label %for.body
+
+for.body:
+ %i.02 = phi i32 [ 0, %entry ], [ %inc, %for.body ], [%inc, %for.second]
+ %inc = add nsw i32 %i.02, 1
+ %cmp = icmp slt i32 %inc, 16
+ br i1 %cmp, label %for.body, label %for.second
+
+for.second:
+ br label %for.body
+}
+
+; Make sure LV legal bails out when there is a non-int, non-ptr phi
+; CHECK-LABEL: "invalid_phi_types"
+; CHECK: LV: Not vectorizing: Found a non-int non-pointer PHI.
+define i32 @invalid_phi_types() {
+entry:
+ br label %for.body
+
+for.body:
+ %i.02 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+ %vec.sum.02 = phi <2 x i32> [ zeroinitializer, %entry ], [ <i32 8, i32 8>, %for.body ]
+ %inc = add nsw i32 %i.02, 1
+ %cmp = icmp slt i32 %inc, 16
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end:
+ ret i32 0
+}
+
+; D40973
+; Make sure LV legal bails out when the loop doesn't have a legal pre-header.
+; CHECK-LABEL: "inc"
+; CHECK: LV: Not vectorizing: Loop doesn't have a legal pre-header.
+define void @inc(i32 %n, i8* %P) {
+ %1 = icmp sgt i32 %n, 0
+ br i1 %1, label %BB1, label %BB2
+
+BB1:
+ indirectbr i8* %P, [label %.lr.ph]
+
+BB2:
+ br label %.lr.ph
+
+.lr.ph:
+ %indvars.iv = phi i32 [ %indvars.iv.next, %.lr.ph ], [ 0, %BB1 ], [ 0, %BB2 ]
+ %indvars.iv.next = add i32 %indvars.iv, 1
+ %exitcond = icmp eq i32 %indvars.iv.next, %n
+ br i1 %exitcond, label %._crit_edge, label %.lr.ph
+
+._crit_edge:
+ ret void
+}
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