[llvm-branch-commits] [llvm] a74941d - Revert "[BasicAA] Handle two unknown sizes for GEPs"

Florian Hahn via llvm-branch-commits llvm-branch-commits at lists.llvm.org
Fri Dec 18 10:03:50 PST 2020


Author: Florian Hahn
Date: 2020-12-18T17:59:12Z
New Revision: a74941da716d29a1d962d17b8112c40a8a45f9e7

URL: https://github.com/llvm/llvm-project/commit/a74941da716d29a1d962d17b8112c40a8a45f9e7
DIFF: https://github.com/llvm/llvm-project/commit/a74941da716d29a1d962d17b8112c40a8a45f9e7.diff

LOG: Revert "[BasicAA] Handle two unknown sizes for GEPs"

Temporarily revert commit 8b1c4e310c2f9686cad925ad81d8e2be10a1ef3c.

After 8b1c4e310c2f the compile-time for `MultiSource/Benchmarks/MiBench/consumer-lame`
dramatically increases with -O3 & LTO, causing issues for builders with
that configuration.

I filed PR48553 with a smallish reproducer that shows a 10-100x compile
time increase.

Added: 
    

Modified: 
    llvm/lib/Analysis/BasicAliasAnalysis.cpp
    llvm/test/Analysis/BasicAA/phi-aa.ll
    llvm/test/Analysis/BasicAA/recphi.ll
    llvm/test/Transforms/LoopVectorize/ARM/pointer_iv.ll
    llvm/test/Transforms/LoopVersioning/exit-block-dominates-rt-check-block.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index 3e22ce84d181..caa0635459b3 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1098,22 +1098,6 @@ AliasResult BasicAAResult::aliasGEP(
     const GEPOperator *GEP1, LocationSize V1Size, const AAMDNodes &V1AAInfo,
     const Value *V2, LocationSize V2Size, const AAMDNodes &V2AAInfo,
     const Value *UnderlyingV1, const Value *UnderlyingV2, AAQueryInfo &AAQI) {
-  // If both accesses are unknown size, we can only check whether the
-  // underlying objects are 
diff erent.
-  if (!V1Size.hasValue() && !V2Size.hasValue()) {
-    // If the other operand is a phi/select, let phi/select handling perform
-    // this check. Otherwise the same recursive walk is done twice.
-    if (!isa<PHINode>(V2) && !isa<SelectInst>(V2)) {
-      AliasResult BaseAlias =
-          aliasCheck(UnderlyingV1, LocationSize::beforeOrAfterPointer(),
-                     AAMDNodes(), UnderlyingV2,
-                     LocationSize::beforeOrAfterPointer(), AAMDNodes(), AAQI);
-      if (BaseAlias == NoAlias)
-        return NoAlias;
-    }
-    return MayAlias;
-  }
-
   DecomposedGEP DecompGEP1 = DecomposeGEPExpression(GEP1, DL, &AC, DT);
   DecomposedGEP DecompGEP2 = DecomposeGEPExpression(V2, DL, &AC, DT);
 
@@ -1172,6 +1156,10 @@ AliasResult BasicAAResult::aliasGEP(
     // instruction.  If one pointer is a GEP with a non-zero index of the other
     // pointer, we know they cannot alias.
 
+    // If both accesses are unknown size, we can't do anything useful here.
+    if (!V1Size.hasValue() && !V2Size.hasValue())
+      return MayAlias;
+
     AliasResult R = aliasCheck(
         UnderlyingV1, LocationSize::beforeOrAfterPointer(), AAMDNodes(),
         V2, V2Size, V2AAInfo, AAQI, nullptr, UnderlyingV2);

diff  --git a/llvm/test/Analysis/BasicAA/phi-aa.ll b/llvm/test/Analysis/BasicAA/phi-aa.ll
index 3446d0bef849..bf5915f1e0fe 100644
--- a/llvm/test/Analysis/BasicAA/phi-aa.ll
+++ b/llvm/test/Analysis/BasicAA/phi-aa.ll
@@ -152,7 +152,8 @@ loop:
 }
 
 ; CHECK-LABEL: phi_and_gep_unknown_size
-; CHECK: NoModRef:   call void @llvm.memset.p0i8.i32(i8* %g, i8 0, i32 %size, i1 false) <->   call void @llvm.memset.p0i8.i32(i8* %z, i8 0, i32 %size, i1 false)
+; CHECK: Just Mod:   call void @llvm.memset.p0i8.i32(i8* %g, i8 0, i32 %size, i1 false) <->   call void @llvm.memset.p0i8.i32(i8* %z, i8 0, i32 %size, i1 false)
+; TODO: This should be NoModRef.
 define void @phi_and_gep_unknown_size(i1 %c, i8* %x, i8* %y, i8* noalias %z, i32 %size) {
 entry:
   br i1 %c, label %true, label %false

diff  --git a/llvm/test/Analysis/BasicAA/recphi.ll b/llvm/test/Analysis/BasicAA/recphi.ll
index 882128a2daf0..7f8bc9d7b668 100644
--- a/llvm/test/Analysis/BasicAA/recphi.ll
+++ b/llvm/test/Analysis/BasicAA/recphi.ll
@@ -267,8 +267,9 @@ exit:
 ; CHECK: NoAlias:  i8* %a, i8* %p.base
 ; CHECK: NoAlias:  i8* %a, i8* %p.outer
 ; CHECK: NoAlias:  i8* %a, i8* %p.outer.next
-; CHECK: NoAlias:  i8* %a, i8* %p.inner
+; CHECK: MayAlias: i8* %a, i8* %p.inner
 ; CHECK: NoAlias:  i8* %a, i8* %p.inner.next
+; TODO: (a, p.inner) could be NoAlias
 define void @nested_loop2(i1 %c, i1 %c2, i8* noalias %p.base) {
 entry:
   %a = alloca i8

diff  --git a/llvm/test/Transforms/LoopVectorize/ARM/pointer_iv.ll b/llvm/test/Transforms/LoopVectorize/ARM/pointer_iv.ll
index b30e342d9a3f..6c6cfa9fadc3 100644
--- a/llvm/test/Transforms/LoopVectorize/ARM/pointer_iv.ll
+++ b/llvm/test/Transforms/LoopVectorize/ARM/pointer_iv.ll
@@ -876,31 +876,62 @@ for.body:
 define hidden void @mult_ptr_iv(i8* noalias nocapture readonly %x, i8* noalias nocapture %z) {
 ; CHECK-LABEL: @mult_ptr_iv(
 ; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[SCEVGEP:%.*]] = getelementptr i8, i8* [[Z:%.*]], i32 3000
+; CHECK-NEXT:    [[SCEVGEP1:%.*]] = getelementptr i8, i8* [[X:%.*]], i32 3000
+; CHECK-NEXT:    [[BOUND0:%.*]] = icmp ugt i8* [[SCEVGEP1]], [[Z]]
+; CHECK-NEXT:    [[BOUND1:%.*]] = icmp ugt i8* [[SCEVGEP]], [[X]]
+; CHECK-NEXT:    [[FOUND_CONFLICT:%.*]] = and i1 [[BOUND0]], [[BOUND1]]
+; CHECK-NEXT:    br i1 [[FOUND_CONFLICT]], label [[FOR_BODY:%.*]], label [[VECTOR_PH:%.*]]
+; CHECK:       vector.ph:
+; CHECK-NEXT:    [[IND_END:%.*]] = getelementptr i8, i8* [[X]], i32 3000
+; CHECK-NEXT:    [[IND_END3:%.*]] = getelementptr i8, i8* [[Z]], i32 3000
 ; CHECK-NEXT:    br label [[VECTOR_BODY:%.*]]
 ; CHECK:       vector.body:
-; CHECK-NEXT:    [[POINTER_PHI:%.*]] = phi i8* [ [[X:%.*]], [[ENTRY:%.*]] ], [ [[PTR_IND:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[POINTER_PHI4:%.*]] = phi i8* [ [[Z:%.*]], [[ENTRY]] ], [ [[PTR_IND5:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[POINTER_PHI:%.*]] = phi i8* [ [[X]], [[VECTOR_PH]] ], [ [[PTR_IND:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[POINTER_PHI5:%.*]] = phi i8* [ [[Z]], [[VECTOR_PH]] ], [ [[PTR_IND6:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr i8, i8* [[POINTER_PHI]], <4 x i32> <i32 0, i32 3, i32 6, i32 9>
-; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr i8, i8* [[POINTER_PHI4]], <4 x i32> <i32 0, i32 3, i32 6, i32 9>
+; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr i8, i8* [[POINTER_PHI5]], <4 x i32> <i32 0, i32 3, i32 6, i32 9>
 ; CHECK-NEXT:    [[TMP2:%.*]] = getelementptr inbounds i8, <4 x i8*> [[TMP0]], i32 1
-; CHECK-NEXT:    [[WIDE_MASKED_GATHER:%.*]] = call <4 x i8> @llvm.masked.gather.v4i8.v4p0i8(<4 x i8*> [[TMP0]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>, <4 x i8> undef)
+; CHECK-NEXT:    [[WIDE_MASKED_GATHER:%.*]] = call <4 x i8> @llvm.masked.gather.v4i8.v4p0i8(<4 x i8*> [[TMP0]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>, <4 x i8> undef), !alias.scope !26
 ; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, <4 x i8*> [[TMP0]], i32 2
-; CHECK-NEXT:    [[WIDE_MASKED_GATHER6:%.*]] = call <4 x i8> @llvm.masked.gather.v4i8.v4p0i8(<4 x i8*> [[TMP2]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>, <4 x i8> undef)
-; CHECK-NEXT:    [[WIDE_MASKED_GATHER7:%.*]] = call <4 x i8> @llvm.masked.gather.v4i8.v4p0i8(<4 x i8*> [[TMP3]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>, <4 x i8> undef)
+; CHECK-NEXT:    [[WIDE_MASKED_GATHER7:%.*]] = call <4 x i8> @llvm.masked.gather.v4i8.v4p0i8(<4 x i8*> [[TMP2]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>, <4 x i8> undef), !alias.scope !26
+; CHECK-NEXT:    [[WIDE_MASKED_GATHER8:%.*]] = call <4 x i8> @llvm.masked.gather.v4i8.v4p0i8(<4 x i8*> [[TMP3]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>, <4 x i8> undef), !alias.scope !26
 ; CHECK-NEXT:    [[TMP4:%.*]] = mul <4 x i8> [[WIDE_MASKED_GATHER]], <i8 10, i8 10, i8 10, i8 10>
-; CHECK-NEXT:    [[TMP5:%.*]] = mul <4 x i8> [[WIDE_MASKED_GATHER]], [[WIDE_MASKED_GATHER6]]
-; CHECK-NEXT:    [[TMP6:%.*]] = mul <4 x i8> [[WIDE_MASKED_GATHER]], [[WIDE_MASKED_GATHER7]]
+; CHECK-NEXT:    [[TMP5:%.*]] = mul <4 x i8> [[WIDE_MASKED_GATHER]], [[WIDE_MASKED_GATHER7]]
+; CHECK-NEXT:    [[TMP6:%.*]] = mul <4 x i8> [[WIDE_MASKED_GATHER]], [[WIDE_MASKED_GATHER8]]
 ; CHECK-NEXT:    [[TMP7:%.*]] = getelementptr inbounds i8, <4 x i8*> [[TMP1]], i32 1
-; CHECK-NEXT:    call void @llvm.masked.scatter.v4i8.v4p0i8(<4 x i8> [[TMP4]], <4 x i8*> [[TMP1]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>)
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4i8.v4p0i8(<4 x i8> [[TMP4]], <4 x i8*> [[TMP1]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>), !alias.scope !29, !noalias !26
 ; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds i8, <4 x i8*> [[TMP1]], i32 2
-; CHECK-NEXT:    call void @llvm.masked.scatter.v4i8.v4p0i8(<4 x i8> [[TMP5]], <4 x i8*> [[TMP7]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>)
-; CHECK-NEXT:    call void @llvm.masked.scatter.v4i8.v4p0i8(<4 x i8> [[TMP6]], <4 x i8*> [[TMP8]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>)
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4i8.v4p0i8(<4 x i8> [[TMP5]], <4 x i8*> [[TMP7]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>), !alias.scope !29, !noalias !26
+; CHECK-NEXT:    call void @llvm.masked.scatter.v4i8.v4p0i8(<4 x i8> [[TMP6]], <4 x i8*> [[TMP8]], i32 1, <4 x i1> <i1 true, i1 true, i1 true, i1 true>), !alias.scope !29, !noalias !26
 ; CHECK-NEXT:    [[INDEX_NEXT]] = add i32 [[INDEX]], 4
 ; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq i32 [[INDEX_NEXT]], 1000
 ; CHECK-NEXT:    [[PTR_IND]] = getelementptr i8, i8* [[POINTER_PHI]], i32 12
-; CHECK-NEXT:    [[PTR_IND5]] = getelementptr i8, i8* [[POINTER_PHI4]], i32 12
-; CHECK-NEXT:    br i1 [[TMP9]], label [[END:%.*]], label [[VECTOR_BODY]], [[LOOP26:!llvm.loop !.*]]
+; CHECK-NEXT:    [[PTR_IND6]] = getelementptr i8, i8* [[POINTER_PHI5]], i32 12
+; CHECK-NEXT:    br i1 [[TMP9]], label [[END:%.*]], label [[VECTOR_BODY]], [[LOOP31:!llvm.loop !.*]]
+; CHECK:       for.body:
+; CHECK-NEXT:    [[X_ADDR_050:%.*]] = phi i8* [ [[INCDEC_PTR2:%.*]], [[FOR_BODY]] ], [ [[X]], [[ENTRY:%.*]] ]
+; CHECK-NEXT:    [[Z_ADDR_049:%.*]] = phi i8* [ [[INCDEC_PTR34:%.*]], [[FOR_BODY]] ], [ [[Z]], [[ENTRY]] ]
+; CHECK-NEXT:    [[I_048:%.*]] = phi i32 [ [[INC:%.*]], [[FOR_BODY]] ], [ 0, [[ENTRY]] ]
+; CHECK-NEXT:    [[INCDEC_PTR:%.*]] = getelementptr inbounds i8, i8* [[X_ADDR_050]], i32 1
+; CHECK-NEXT:    [[TMP10:%.*]] = load i8, i8* [[X_ADDR_050]], align 1
+; CHECK-NEXT:    [[INCDEC_PTR1:%.*]] = getelementptr inbounds i8, i8* [[X_ADDR_050]], i32 2
+; CHECK-NEXT:    [[TMP11:%.*]] = load i8, i8* [[INCDEC_PTR]], align 1
+; CHECK-NEXT:    [[INCDEC_PTR2]] = getelementptr inbounds i8, i8* [[X_ADDR_050]], i32 3
+; CHECK-NEXT:    [[TMP12:%.*]] = load i8, i8* [[INCDEC_PTR1]], align 1
+; CHECK-NEXT:    [[MUL:%.*]] = mul i8 [[TMP10]], 10
+; CHECK-NEXT:    [[MUL1:%.*]] = mul i8 [[TMP10]], [[TMP11]]
+; CHECK-NEXT:    [[MUL2:%.*]] = mul i8 [[TMP10]], [[TMP12]]
+; CHECK-NEXT:    [[INCDEC_PTR32:%.*]] = getelementptr inbounds i8, i8* [[Z_ADDR_049]], i32 1
+; CHECK-NEXT:    store i8 [[MUL]], i8* [[Z_ADDR_049]], align 1
+; CHECK-NEXT:    [[INCDEC_PTR33:%.*]] = getelementptr inbounds i8, i8* [[Z_ADDR_049]], i32 2
+; CHECK-NEXT:    store i8 [[MUL1]], i8* [[INCDEC_PTR32]], align 1
+; CHECK-NEXT:    [[INCDEC_PTR34]] = getelementptr inbounds i8, i8* [[Z_ADDR_049]], i32 3
+; CHECK-NEXT:    store i8 [[MUL2]], i8* [[INCDEC_PTR33]], align 1
+; CHECK-NEXT:    [[INC]] = add nuw i32 [[I_048]], 1
+; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp eq i32 [[INC]], 1000
+; CHECK-NEXT:    br i1 [[EXITCOND]], label [[END]], label [[FOR_BODY]], [[LOOP32:!llvm.loop !.*]]
 ; CHECK:       end:
 ; CHECK-NEXT:    ret void
 ;

diff  --git a/llvm/test/Transforms/LoopVersioning/exit-block-dominates-rt-check-block.ll b/llvm/test/Transforms/LoopVersioning/exit-block-dominates-rt-check-block.ll
index afb5ecfa0288..960c890516c8 100644
--- a/llvm/test/Transforms/LoopVersioning/exit-block-dominates-rt-check-block.ll
+++ b/llvm/test/Transforms/LoopVersioning/exit-block-dominates-rt-check-block.ll
@@ -12,7 +12,7 @@
 
 @c1 = external global i16
 
-define void @f(i16 %a, [1 x i32]* %p) {
+define void @f(i16 %a) {
   br label %bb0
 
 bb0:
@@ -24,9 +24,9 @@ bb1:
 
 bb2:
   %tmp2 = phi i16 [ %tmp1, %bb1 ], [ %tmp3, %bb2 ]
-  %tmp4 = getelementptr inbounds [1 x i32], [1 x i32]* %p, i32 0, i32 4
+  %tmp4 = getelementptr inbounds [1 x i32], [1 x i32]* undef, i32 0, i32 4
   store i32 1, i32* %tmp4
-  %tmp5 = getelementptr inbounds [1 x i32], [1 x i32]* %p, i32 0, i32 9
+  %tmp5 = getelementptr inbounds [1 x i32], [1 x i32]* undef, i32 0, i32 9
   store i32 0, i32* %tmp5
   %tmp3 = add i16 %tmp2, 1
   store i16 %tmp2, i16* @c1


        


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