[llvm] b96114c - [SCEV] Remove premature assert. PR46786

[Max Kazantsev via llvm-commits]

Author: Max Kazantsev
Date: 2020-07-22T15:43:16+07:00
New Revision: b96114c1e1fc4448ea966bce013706359aee3fa9

URL: https://github.com/llvm/llvm-project/commit/b96114c1e1fc4448ea966bce013706359aee3fa9
DIFF: https://github.com/llvm/llvm-project/commit/b96114c1e1fc4448ea966bce013706359aee3fa9.diff

LOG: [SCEV] Remove premature assert. PR46786

This assert was added to verify assumption that GEP's SCEV will be of pointer type,
basing on fact that it should be a SCEVAddExpr with (at least) last operand being
pointer. Two notes:
- GEP's SCEV does not have to be a SCEVAddExpr after all simplifications;
- In current state, GEP's SCEV does not have to have at least one pointer operands
  (all of them can become int during the transforms).

However, we might want to be at a point where it is true. We are currently removing
this assert and will try to enumerate the cases where "is pointer" notion might be
lost during the transforms. When all of them are fixed, we can return it.

Differential Revision: https://reviews.llvm.org/D84294
Reviewed By: lebedev.ri

Added: 
    llvm/test/Analysis/ScalarEvolution/pr46786.ll

Modified: 
    llvm/lib/Analysis/ScalarEvolution.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 755a4e968521..a961be8cc35e 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -3317,10 +3317,7 @@ ScalarEvolution::getGEPExpr(GEPOperator *GEP,
   }
 
   // Add the total offset from all the GEP indices to the base.
-  auto *GEPExpr = getAddExpr(BaseExpr, TotalOffset, Wrap);
-  assert(BaseExpr->getType() == GEPExpr->getType() &&
-         "GEP should not change type mid-flight.");
-  return GEPExpr;
+  return getAddExpr(BaseExpr, TotalOffset, Wrap);
 }
 
 std::tuple<SCEV *, FoldingSetNodeID, void *>

diff  --git a/llvm/test/Analysis/ScalarEvolution/pr46786.ll b/llvm/test/Analysis/ScalarEvolution/pr46786.ll
new file mode 100644
index 000000000000..21a65702b3a3
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/pr46786.ll
@@ -0,0 +1,37 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py
+; RUN: opt < %s -analyze -enable-new-pm=0 -scalar-evolution | FileCheck %s
+; RUN: opt < %s -disable-output "-passes=print<scalar-evolution>" 2>&1 | FileCheck %s
+
+source_filename = "input.cpp"
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+
+; Function Attrs: nofree
+define i8* @FSE_decompress_usingDTable(i8* %arg, i32 %arg1, i32 %arg2, i32 %arg3) local_unnamed_addr #0 {
+; CHECK-LABEL: 'FSE_decompress_usingDTable'
+; CHECK-NEXT:  Classifying expressions for: @FSE_decompress_usingDTable
+; CHECK-NEXT:    %i = getelementptr inbounds i8, i8* %arg, i32 %arg2
+; CHECK-NEXT:    --> (%arg2 + %arg)<nsw> U: full-set S: full-set
+; CHECK-NEXT:    %i4 = sub nsw i32 0, %arg1
+; CHECK-NEXT:    --> (-1 * %arg1) U: full-set S: full-set
+; CHECK-NEXT:    %i5 = getelementptr inbounds i8, i8* %i, i32 %i4
+; CHECK-NEXT:    --> ((-1 * %arg1) + %arg2 + %arg) U: full-set S: full-set
+; CHECK-NEXT:    %i7 = select i1 %i6, i32 %arg2, i32 %arg1
+; CHECK-NEXT:    --> ((-1 * %arg) + (((-1 * %arg1) + %arg2 + %arg) umin %arg) + %arg1) U: full-set S: full-set
+; CHECK-NEXT:    %i8 = sub i32 %arg3, %i7
+; CHECK-NEXT:    --> ((-1 * (((-1 * %arg1) + %arg2 + %arg) umin %arg)) + (-1 * %arg1) + %arg3 + %arg) U: full-set S: full-set
+; CHECK-NEXT:    %i9 = getelementptr inbounds i8, i8* %arg, i32 %i8
+; CHECK-NEXT:    --> ((2 * %arg) + (-1 * (((-1 * %arg1) + %arg2 + %arg) umin %arg)) + (-1 * %arg1) + %arg3) U: full-set S: full-set
+; CHECK-NEXT:  Determining loop execution counts for: @FSE_decompress_usingDTable
+;
+bb:
+  %i = getelementptr inbounds i8, i8* %arg, i32 %arg2
+  %i4 = sub nsw i32 0, %arg1
+  %i5 = getelementptr inbounds i8, i8* %i, i32 %i4
+  %i6 = icmp ult i8* %i5, %arg
+  %i7 = select i1 %i6, i32 %arg2, i32 %arg1
+  %i8 = sub i32 %arg3, %i7
+  %i9 = getelementptr inbounds i8, i8* %arg, i32 %i8
+  ret i8* %i9
+}
+
+attributes #0 = { nofree }