[ForwardOpTree] Support read-only value uses.

Read-only values (values defined before the SCoP) require special
handing with -polly-analyze-read-only-scalars=true (which is the
default). If active, each use of a value requires a read access.
When a copied value uses a read-only value, we must also ensure that
such a MemoryAccess is available or is created.

Differential Revision: https://reviews.llvm.org/D35764

llvm-svn: 308876

1 files changed, 84 insertions, 0 deletions

diff --git a/polly/test/ForwardOpTree/forward_readonly.ll b/polly/test/ForwardOpTree/forward_readonly.ll
new file mode 100644
index 00000000000..ca514cfc606
--- /dev/null
+++ b/polly/test/ForwardOpTree/forward_readonly.ll
@@ -0,0 +1,84 @@
+; RUN: opt %loadPolly -polly-analyze-read-only-scalars=true  -polly-optree -analyze < %s | FileCheck %s -match-full-lines -check-prefixes=STATS,MODEL
+; RUN: opt %loadPolly -polly-analyze-read-only-scalars=false -polly-optree -analyze < %s | FileCheck %s -match-full-lines -check-prefixes=STATS,NOMODEL
+;
+; Move %val to %bodyB, so %bodyA can be removed (by -polly-simplify)
+;
+; for (int j = 0; j < n; j += 1) {
+; bodyA:
+;   double val = arg + 21.0;
+;
+; bodyB:
+;   A[0] = val;
+; }
+;
+define void @func(i32 %n, double* noalias nonnull %A, double %arg) {
+entry:
+  br label %for
+
+for:
+  %j = phi i32 [0, %entry], [%j.inc, %inc]
+  %j.cmp = icmp slt i32 %j, %n
+  br i1 %j.cmp, label %bodyA, label %exit
+
+    bodyA:
+      %val = fadd double %arg, 21.0
+      br label %bodyB
+
+    bodyB:
+      store double %val, double* %A
+      br label %inc
+
+inc:
+  %j.inc = add nuw nsw i32 %j, 1
+  br label %for
+
+exit:
+  br label %return
+
+return:
+  ret void
+}
+
+
+; STATS: Statistics {
+; STATS:     Instructions copied: 1
+; STATS:     Read-only accesses copied: 1
+; STATS:     Operand trees forwarded: 1
+; STATS:     Statements with forwarded operand trees: 1
+; STATS: }
+
+; MODEL:      After statements {
+; MODEL-NEXT:     Stmt_bodyA
+; MODEL-NEXT:             ReadAccess :=       [Reduction Type: NONE] [Scalar: 1]
+; MODEL-NEXT:                 [n] -> { Stmt_bodyA[i0] -> MemRef_arg[] };
+; MODEL-NEXT:             MustWriteAccess :=  [Reduction Type: NONE] [Scalar: 1]
+; MODEL-NEXT:                 [n] -> { Stmt_bodyA[i0] -> MemRef_val[] };
+; MODEL-NEXT:             Instructions {
+; MODEL-NEXT:                   %val = fadd double %arg, 2.100000e+01
+; MODEL-NEXT:                 }
+; MODEL-NEXT:     Stmt_bodyB
+; MODEL-NEXT:             MustWriteAccess :=  [Reduction Type: NONE] [Scalar: 0]
+; MODEL-NEXT:                 [n] -> { Stmt_bodyB[i0] -> MemRef_A[0] };
+; MODEL-NEXT:             ReadAccess :=       [Reduction Type: NONE] [Scalar: 1]
+; MODEL-NEXT:                 [n] -> { Stmt_bodyB[i0] -> MemRef_arg[] };
+; MODEL-NEXT:             Instructions {
+; MODEL-NEXT:                   %val = fadd double %arg, 2.100000e+01
+; MODEL-NEXT:                   store double %val, double* %A
+; MODEL-NEXT:                 }
+; MODEL-NEXT: }
+
+; NOMODEL:      After statements {
+; NOMODEL-NEXT:     Stmt_bodyA
+; NOMODEL-NEXT:             MustWriteAccess :=  [Reduction Type: NONE] [Scalar: 1]
+; NOMODEL-NEXT:                 [n] -> { Stmt_bodyA[i0] -> MemRef_val[] };
+; NOMODEL-NEXT:             Instructions {
+; NOMODEL-NEXT:                   %val = fadd double %arg, 2.100000e+01
+; NOMODEL-NEXT:                 }
+; NOMODEL-NEXT:     Stmt_bodyB
+; NOMODEL-NEXT:             MustWriteAccess :=  [Reduction Type: NONE] [Scalar: 0]
+; NOMODEL-NEXT:                 [n] -> { Stmt_bodyB[i0] -> MemRef_A[0] };
+; NOMODEL-NEXT:             Instructions {
+; NOMODEL-NEXT:                   %val = fadd double %arg, 2.100000e+01
+; NOMODEL-NEXT:                   store double %val, double* %A
+; NOMODEL-NEXT:                 }
+; NOMODEL-NEXT: }