3cdf87940f
This patch adds a basic loop fusion pass. It will fuse loops that conform to the following 4 conditions: 1. Adjacent (no code between them) 2. Control flow equivalent (if one loop executes, the other loop executes) 3. Identical bounds (both loops iterate the same number of iterations) 4. No negative distance dependencies between the loop bodies. The pass does not make any changes to the IR to create opportunities for fusion. Instead, it checks if the necessary conditions are met and if so it fuses two loops together. The pass has not been added to the pass pipeline yet, and thus is not enabled by default. It can be run stand alone using the -loop-fusion option. Differential Revision: https://reviews.llvm.org/D55851 llvm-svn: 358607
121 lines
4.5 KiB
LLVM
121 lines
4.5 KiB
LLVM
; RUN: opt -S -loop-fusion < %s | FileCheck %s
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;
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; int A[1024][1024];
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; int B[1024][1024];
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;
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; #define EXPENSIVE_PURE_COMPUTATION(i) ((i - 3) * (i + 3) % i)
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;
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; void dep_free() {
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;
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; for (int i = 0; i < 100; i++)
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; for (int j = 0; j < 100; j++)
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; A[i][j] = EXPENSIVE_PURE_COMPUTATION(i);
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;
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; for (int i = 0; i < 100; i++)
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; for (int j = 0; j < 100; j++)
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; B[i][j] = EXPENSIVE_PURE_COMPUTATION(i);
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; }
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;
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@A = common global [1024 x [1024 x i32]] zeroinitializer, align 16
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@B = common global [1024 x [1024 x i32]] zeroinitializer, align 16
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; CHECK: void @dep_free
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; CHECK-NEXT: bb:
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; CHECK-NEXT: br label %[[LOOP1HEADER:bb[0-9]+]]
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; CHECK: [[LOOP1HEADER]]
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; CHECK: br i1 %exitcond12, label %[[LOOP3PREHEADER:bb[0-9]+.preheader]], label %[[LOOP2HEADER:bb[0-9]+]]
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; CHECK: [[LOOP3PREHEADER]]
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; CHECK: br label %[[LOOP3HEADER:bb[0-9]+]]
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; CHECK: [[LOOP3HEADER]]
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; CHECK: br i1 %exitcond9, label %[[LOOP3BODY:bb[0-9]+]], label %[[LOOP1LATCH:bb[0-9]+]]
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; CHECK: [[LOOP1LATCH]]
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; CHECK: br label %[[LOOP2HEADER:bb[0-9]+]]
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; CHECK: [[LOOP2HEADER]]
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; CHECK: br i1 %exitcond6, label %[[LOOP4PREHEADER:bb[0-9]+.preheader]], label %[[LOOP2EXITBLOCK:bb[0-9]+]]
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; CHECK: [[LOOP4PREHEADER]]
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; CHECK: br label %[[LOOP4HEADER:bb[0-9]+]]
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; CHECK: [[LOOP2EXITBLOCK]]
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; CHECK-NEXT: br label %[[FUNCEXIT:bb[0-9]+]]
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; CHECK: [[LOOP4HEADER]]
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; CHECK: br i1 %exitcond, label %[[LOOP4BODY:bb[0-9]+]], label %[[LOOP2LATCH:bb[0-9]+]]
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; CHECK: [[LOOP2LATCH]]
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; CHECK: br label %[[LOOP1HEADER:bb[0-9]+]]
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; CHECK: [[FUNCEXIT]]
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; CHECK: ret void
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; TODO: The current version of loop fusion does not allow the inner loops to be
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; fused because they are not control flow equivalent and adjacent. These are
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; limitations that can be addressed in future improvements to fusion.
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define void @dep_free() {
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bb:
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br label %bb13
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bb13: ; preds = %bb27, %bb
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%indvars.iv10 = phi i64 [ %indvars.iv.next11, %bb27 ], [ 0, %bb ]
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%.0 = phi i32 [ 0, %bb ], [ %tmp28, %bb27 ]
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%exitcond12 = icmp ne i64 %indvars.iv10, 100
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br i1 %exitcond12, label %bb16, label %bb30
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bb16: ; preds = %bb25, %bb13
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%indvars.iv7 = phi i64 [ %indvars.iv.next8, %bb25 ], [ 0, %bb13 ]
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%exitcond9 = icmp ne i64 %indvars.iv7, 100
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br i1 %exitcond9, label %bb18, label %bb27
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bb18: ; preds = %bb16
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%tmp = add nsw i32 %.0, -3
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%tmp19 = add nuw nsw i64 %indvars.iv10, 3
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%tmp20 = trunc i64 %tmp19 to i32
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%tmp21 = mul nsw i32 %tmp, %tmp20
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%tmp22 = trunc i64 %indvars.iv10 to i32
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%tmp23 = srem i32 %tmp21, %tmp22
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%tmp24 = getelementptr inbounds [1024 x [1024 x i32]], [1024 x [1024 x i32]]* @A, i64 0, i64 %indvars.iv10, i64 %indvars.iv7
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store i32 %tmp23, i32* %tmp24, align 4
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br label %bb25
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bb25: ; preds = %bb18
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%indvars.iv.next8 = add nuw nsw i64 %indvars.iv7, 1
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br label %bb16
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bb27: ; preds = %bb16
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%indvars.iv.next11 = add nuw nsw i64 %indvars.iv10, 1
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%tmp28 = add nuw nsw i32 %.0, 1
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br label %bb13
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bb30: ; preds = %bb45, %bb13
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%indvars.iv4 = phi i64 [ %indvars.iv.next5, %bb45 ], [ 0, %bb13 ]
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%.02 = phi i32 [ 0, %bb13 ], [ %tmp46, %bb45 ]
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%exitcond6 = icmp ne i64 %indvars.iv4, 100
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br i1 %exitcond6, label %bb33, label %bb31
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bb31: ; preds = %bb30
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br label %bb47
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bb33: ; preds = %bb43, %bb30
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%indvars.iv = phi i64 [ %indvars.iv.next, %bb43 ], [ 0, %bb30 ]
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%exitcond = icmp ne i64 %indvars.iv, 100
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br i1 %exitcond, label %bb35, label %bb45
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bb35: ; preds = %bb33
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%tmp36 = add nsw i32 %.02, -3
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%tmp37 = add nuw nsw i64 %indvars.iv4, 3
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%tmp38 = trunc i64 %tmp37 to i32
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%tmp39 = mul nsw i32 %tmp36, %tmp38
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%tmp40 = trunc i64 %indvars.iv4 to i32
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%tmp41 = srem i32 %tmp39, %tmp40
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%tmp42 = getelementptr inbounds [1024 x [1024 x i32]], [1024 x [1024 x i32]]* @B, i64 0, i64 %indvars.iv4, i64 %indvars.iv
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store i32 %tmp41, i32* %tmp42, align 4
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br label %bb43
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bb43: ; preds = %bb35
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%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
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br label %bb33
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bb45: ; preds = %bb33
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%indvars.iv.next5 = add nuw nsw i64 %indvars.iv4, 1
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%tmp46 = add nuw nsw i32 %.02, 1
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br label %bb30
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bb47: ; preds = %bb31
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ret void
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}
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