[flang-commits] [flang] 81c6693 - [flang] Prevent any non constant result extent to be inlined on caller side

[Jean Perier via flang-commits]

Author: Jean Perier
Date: 2022-01-19T19:15:49+01:00
New Revision: 81c66933292b8f7ea105122f39e0a06038744a88

URL: https://github.com/llvm/llvm-project/commit/81c66933292b8f7ea105122f39e0a06038744a88
DIFF: https://github.com/llvm/llvm-project/commit/81c66933292b8f7ea105122f39e0a06038744a88.diff

LOG: [flang] Prevent any non constant result extent to be inlined on caller side

UBOUND, SIZE, and SHAPE folding was still creating expressions that are
invalid on the caller side without the call expression context.
A previous patch intended to deal with this situation (https://reviews.llvm.org/D116933)
but it assumed the return expression would be a descriptor inquiry to
the result symbol, which is not the case if the extent expression is
"scope invariant" inside the called subroutine (e.g., referring to
intent(in) dummy arguments). Simply prevent folding from inlining non
constant extent expression on the caller side.

Folding could be later improved by having ad-hoc folding for UBOUND, SIZE, and
SHAPE on function references where it could try replacing the dummy symbols
by the actual expression, but this is left as a possible later improvement.

Differential Revision: https://reviews.llvm.org/D117686

Added: 
    

Modified: 
    flang/lib/Evaluate/shape.cpp
    flang/test/Evaluate/rewrite01.f90

Removed: 
    


################################################################################
diff  --git a/flang/lib/Evaluate/shape.cpp b/flang/lib/Evaluate/shape.cpp
index 3411933bb4354..21db9a4b82b2c 100644
--- a/flang/lib/Evaluate/shape.cpp
+++ b/flang/lib/Evaluate/shape.cpp
@@ -560,13 +560,12 @@ auto GetShapeHelper::operator()(const Symbol &symbol) const -> Result {
             if (subp.isFunction()) {
               auto resultShape{(*this)(subp.result())};
               if (resultShape && !useResultSymbolShape_) {
-                // Ensure the shape does not contain descriptor inquiries, they
-                // may refer to symbols belonging to the called subprogram scope
-                // that are meaningless on the caller side without the related
-                // call expression.
+                // Ensure the shape is constant. Otherwise, it may be referring
+                // to symbols that belong to the subroutine scope and are
+                // meaningless on the caller side without the related call
+                // expression.
                 for (auto extent : *resultShape) {
-                  if (extent &&
-                      std::holds_alternative<DescriptorInquiry>(extent->u)) {
+                  if (extent && !IsConstantExpr(*extent)) {
                     return std::nullopt;
                   }
                 }

diff  --git a/flang/test/Evaluate/rewrite01.f90 b/flang/test/Evaluate/rewrite01.f90
index 5890d372ac2e6..f5fc57899f162 100644
--- a/flang/test/Evaluate/rewrite01.f90
+++ b/flang/test/Evaluate/rewrite01.f90
@@ -12,6 +12,17 @@ function returns_array(n, m)
   returns_array = 0
 end function
 
+function returns_array_2(n)
+  integer, intent(in) :: n
+  integer :: returns_array_2(n)
+  returns_array_2 = 0
+end function
+
+function returns_array_3()
+  integer :: returns_array_3(7:46+2)
+  returns_array_3 = 0
+end function
+
 subroutine ubound_test(x, n, m)
   integer :: x(n, m)
   !CHECK: PRINT *, [INTEGER(4)::int(size(x,dim=1),kind=4),int(size(x,dim=2),kind=4)]
@@ -20,6 +31,10 @@ subroutine ubound_test(x, n, m)
   print *, ubound(returns_array(n, m))
   !CHECK: PRINT *, ubound(returns_array(n,m),dim=1_4)
   print *, ubound(returns_array(n, m), dim=1)
+  !CHECK: PRINT *, ubound(returns_array_2(m))
+  print *, ubound(returns_array_2(m))
+  !CHECK: PRINT *, 42_8
+  print *, ubound(returns_array_3(), dim=1, kind=8)
 end subroutine
 
 subroutine size_test(x, n, m)
@@ -30,6 +45,10 @@ subroutine size_test(x, n, m)
   print *, size(returns_array(n, m))
   !CHECK: PRINT *, size(returns_array(n,m),dim=1_4)
   print *, size(returns_array(n, m), dim=1)
+  !CHECK: PRINT *, size(returns_array_2(m))
+  print *, size(returns_array_2(m))
+  !CHECK: PRINT *, 42_8
+  print *, size(returns_array_3(), kind=8)
 end subroutine
 
 subroutine shape_test(x, n, m)
@@ -38,6 +57,10 @@ subroutine shape_test(x, n, m)
   print *, shape(x)
   !CHECK: PRINT *, shape(returns_array(n,m))
   print *, shape(returns_array(n, m))
+  !CHECK: PRINT *, shape(returns_array_2(m))
+  print *, shape(returns_array_2(m))
+  !CHECK: PRINT *, [INTEGER(8)::42_8]
+  print *, shape(returns_array_3(), kind=8)
 end subroutine
 
 subroutine lbound_test(x, n, m)
@@ -48,5 +71,9 @@ subroutine lbound_test(x, n, m)
   print *, lbound(returns_array(n, m))
   !CHECK: PRINT *, 1_4
   print *, lbound(returns_array(n, m), dim=1)
+  !CHECK: PRINT *, 1_4
+  print *, lbound(returns_array_2(m), dim=1)
+  !CHECK: PRINT *, 1_4
+  print *, lbound(returns_array_3(), dim=1)
 end subroutine
 end module