dependence analysis
Patch from Preston Briggs <preston.briggs@gmail.com>.
This is an updated version of the dependence-analysis patch, including an MIV
test based on Banerjee's inequalities.
It's a fairly complete implementation of the paper
Practical Dependence Testing
Gina Goff, Ken Kennedy, and Chau-Wen Tseng
PLDI 1991
It cannot yet propagate constraints between coupled RDIV subscripts (discussed
in Section 5.3.2 of the paper).
It's organized as a FunctionPass with a single entry point that supports testing
for dependence between two instructions in a function. If there's no dependence,
it returns null. If there's a dependence, it returns a pointer to a Dependence
which can be queried about details (what kind of dependence, is it loop
independent, direction and distance vector entries, etc). I haven't included
every imaginable feature, but there's a good selection that should be adequate
for supporting many loop transformations. Of course, it can be extended as
necessary.
Included in the patch file are many test cases, commented with C code showing
the loops and array references.
llvm-svn: 165708
diff --git a/llvm/test/Analysis/DependenceAnalysis/WeakCrossingSIV.ll b/llvm/test/Analysis/DependenceAnalysis/WeakCrossingSIV.ll
new file mode 100644
index 0000000..343e8f4
--- /dev/null
+++ b/llvm/test/Analysis/DependenceAnalysis/WeakCrossingSIV.ll
@@ -0,0 +1,220 @@
+; RUN: opt < %s -analyze -basicaa -da | FileCheck %s
+
+; ModuleID = 'WeakCrossingSIV.bc'
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.6.0"
+
+
+;; for (long unsigned i = 0; i < n; i++)
+;; A[1 + n*i] = ...
+;; ... = A[1 - n*i];
+
+define void @weakcrossing0(i32* %A, i32* %B, i64 %n) nounwind uwtable ssp {
+entry:
+ %cmp1 = icmp eq i64 %n, 0
+ br i1 %cmp1, label %for.end, label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %i.03 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
+ %B.addr.02 = phi i32* [ %incdec.ptr, %for.body ], [ %B, %entry ]
+ %conv = trunc i64 %i.03 to i32
+ %mul = mul i64 %i.03, %n
+ %add = add i64 %mul, 1
+ %arrayidx = getelementptr inbounds i32* %A, i64 %add
+ store i32 %conv, i32* %arrayidx, align 4
+ %mul1 = mul i64 %i.03, %n
+ %sub = sub i64 1, %mul1
+ %arrayidx2 = getelementptr inbounds i32* %A, i64 %sub
+ %0 = load i32* %arrayidx2, align 4
+; CHECK: da analyze - flow [0|<]!
+ %incdec.ptr = getelementptr inbounds i32* %B.addr.02, i64 1
+ store i32 %0, i32* %B.addr.02, align 4
+ %inc = add i64 %i.03, 1
+ %cmp = icmp ult i64 %inc, %n
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body, %entry
+ ret void
+}
+
+
+;; for (long unsigned i = 0; i < n; i++)
+;; A[n + i] = ...
+;; ... = A[1 + n - i];
+
+define void @weakcrossing1(i32* %A, i32* %B, i64 %n) nounwind uwtable ssp {
+entry:
+ %cmp1 = icmp eq i64 %n, 0
+ br i1 %cmp1, label %for.end, label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %i.03 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
+ %B.addr.02 = phi i32* [ %incdec.ptr, %for.body ], [ %B, %entry ]
+ %conv = trunc i64 %i.03 to i32
+ %add = add i64 %i.03, %n
+ %arrayidx = getelementptr inbounds i32* %A, i64 %add
+ store i32 %conv, i32* %arrayidx, align 4
+ %add1 = add i64 %n, 1
+ %sub = sub i64 %add1, %i.03
+ %arrayidx2 = getelementptr inbounds i32* %A, i64 %sub
+ %0 = load i32* %arrayidx2, align 4
+; CHECK: da analyze - flow [<>] splitable!
+; CHECK: da analyze - split level = 1, iteration = 0!
+ %incdec.ptr = getelementptr inbounds i32* %B.addr.02, i64 1
+ store i32 %0, i32* %B.addr.02, align 4
+ %inc = add i64 %i.03, 1
+ %cmp = icmp ult i64 %inc, %n
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body, %entry
+ ret void
+}
+
+
+;; for (long unsigned i = 0; i < 3; i++)
+;; A[i] = ...
+;; ... = A[6 - i];
+
+define void @weakcrossing2(i32* %A, i32* %B, i64 %n) nounwind uwtable ssp {
+entry:
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %i.02 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
+ %B.addr.01 = phi i32* [ %B, %entry ], [ %incdec.ptr, %for.body ]
+ %conv = trunc i64 %i.02 to i32
+ %arrayidx = getelementptr inbounds i32* %A, i64 %i.02
+ store i32 %conv, i32* %arrayidx, align 4
+ %sub = sub i64 6, %i.02
+ %arrayidx1 = getelementptr inbounds i32* %A, i64 %sub
+ %0 = load i32* %arrayidx1, align 4
+; CHECK: da analyze - none!
+ %incdec.ptr = getelementptr inbounds i32* %B.addr.01, i64 1
+ store i32 %0, i32* %B.addr.01, align 4
+ %inc = add i64 %i.02, 1
+ %cmp = icmp ult i64 %inc, 3
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body
+ ret void
+}
+
+
+;; for (long unsigned i = 0; i < 4; i++)
+;; A[i] = ...
+;; ... = A[6 - i];
+
+define void @weakcrossing3(i32* %A, i32* %B, i64 %n) nounwind uwtable ssp {
+entry:
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %i.02 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
+ %B.addr.01 = phi i32* [ %B, %entry ], [ %incdec.ptr, %for.body ]
+ %conv = trunc i64 %i.02 to i32
+ %arrayidx = getelementptr inbounds i32* %A, i64 %i.02
+ store i32 %conv, i32* %arrayidx, align 4
+ %sub = sub i64 6, %i.02
+ %arrayidx1 = getelementptr inbounds i32* %A, i64 %sub
+ %0 = load i32* %arrayidx1, align 4
+; CHECK: da analyze - flow [0|<]!
+ %incdec.ptr = getelementptr inbounds i32* %B.addr.01, i64 1
+ store i32 %0, i32* %B.addr.01, align 4
+ %inc = add i64 %i.02, 1
+ %cmp = icmp ult i64 %inc, 4
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body
+ ret void
+}
+
+
+;; for (long unsigned i = 0; i < 10; i++)
+;; A[i] = ...
+;; ... = A[-6 - i];
+
+define void @weakcrossing4(i32* %A, i32* %B, i64 %n) nounwind uwtable ssp {
+entry:
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %i.02 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
+ %B.addr.01 = phi i32* [ %B, %entry ], [ %incdec.ptr, %for.body ]
+ %conv = trunc i64 %i.02 to i32
+ %arrayidx = getelementptr inbounds i32* %A, i64 %i.02
+ store i32 %conv, i32* %arrayidx, align 4
+ %sub = sub i64 -6, %i.02
+ %arrayidx1 = getelementptr inbounds i32* %A, i64 %sub
+ %0 = load i32* %arrayidx1, align 4
+; CHECK: da analyze - none!
+ %incdec.ptr = getelementptr inbounds i32* %B.addr.01, i64 1
+ store i32 %0, i32* %B.addr.01, align 4
+ %inc = add i64 %i.02, 1
+ %cmp = icmp ult i64 %inc, 10
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body
+ ret void
+}
+
+
+;; for (long unsigned i = 0; i < n; i++)
+;; A[3*i] = ...
+;; ... = A[5 - 3*i];
+
+define void @weakcrossing5(i32* %A, i32* %B, i64 %n) nounwind uwtable ssp {
+entry:
+ %cmp1 = icmp eq i64 %n, 0
+ br i1 %cmp1, label %for.end, label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %i.03 = phi i64 [ %inc, %for.body ], [ 0, %entry ]
+ %B.addr.02 = phi i32* [ %incdec.ptr, %for.body ], [ %B, %entry ]
+ %conv = trunc i64 %i.03 to i32
+ %mul = mul i64 %i.03, 3
+ %arrayidx = getelementptr inbounds i32* %A, i64 %mul
+ store i32 %conv, i32* %arrayidx, align 4
+ %0 = mul i64 %i.03, -3
+ %sub = add i64 %0, 5
+ %arrayidx2 = getelementptr inbounds i32* %A, i64 %sub
+ %1 = load i32* %arrayidx2, align 4
+; CHECK: da analyze - none!
+ %incdec.ptr = getelementptr inbounds i32* %B.addr.02, i64 1
+ store i32 %1, i32* %B.addr.02, align 4
+ %inc = add i64 %i.03, 1
+ %cmp = icmp ult i64 %inc, %n
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body, %entry
+ ret void
+}
+
+
+;; for (long unsigned i = 0; i < 4; i++)
+;; A[i] = ...
+;; ... = A[5 - i];
+
+define void @weakcrossing6(i32* %A, i32* %B, i64 %n) nounwind uwtable ssp {
+entry:
+ br label %for.body
+
+for.body: ; preds = %for.body, %entry
+ %i.02 = phi i64 [ 0, %entry ], [ %inc, %for.body ]
+ %B.addr.01 = phi i32* [ %B, %entry ], [ %incdec.ptr, %for.body ]
+ %conv = trunc i64 %i.02 to i32
+ %arrayidx = getelementptr inbounds i32* %A, i64 %i.02
+ store i32 %conv, i32* %arrayidx, align 4
+ %sub = sub i64 5, %i.02
+ %arrayidx1 = getelementptr inbounds i32* %A, i64 %sub
+ %0 = load i32* %arrayidx1, align 4
+; CHECK: da analyze - flow [<>] splitable!
+; CHECK: da analyze - split level = 1, iteration = 2!
+ %incdec.ptr = getelementptr inbounds i32* %B.addr.01, i64 1
+ store i32 %0, i32* %B.addr.01, align 4
+ %inc = add i64 %i.02, 1
+ %cmp = icmp ult i64 %inc, 4
+ br i1 %cmp, label %for.body, label %for.end
+
+for.end: ; preds = %for.body
+ ret void
+}