diff options
Diffstat (limited to 'llvm/test')
| -rw-r--r-- | llvm/test/Analysis/BlockFrequencyInfo/irreducible.ll | 337 |
1 files changed, 281 insertions, 56 deletions
diff --git a/llvm/test/Analysis/BlockFrequencyInfo/irreducible.ll b/llvm/test/Analysis/BlockFrequencyInfo/irreducible.ll index dd4dd9ed792..af4ad15d9c1 100644 --- a/llvm/test/Analysis/BlockFrequencyInfo/irreducible.ll +++ b/llvm/test/Analysis/BlockFrequencyInfo/irreducible.ll @@ -34,16 +34,28 @@ return: !0 = metadata !{metadata !"branch_weights", i32 1, i32 7} !1 = metadata !{metadata !"branch_weights", i32 3, i32 4} -; The current BlockFrequencyInfo algorithm doesn't handle multiple entrances -; into a loop very well. The frequencies assigned to blocks in the loop are -; predictable (and not absurd), but also not correct and therefore not worth -; testing. +; Irreducible control flow +; ======================== ; -; There are two testcases below. +; LoopInfo defines a loop as a non-trivial SCC dominated by a single block, +; called the header. A given loop, L, can have sub-loops, which are loops +; within the subgraph of L that excludes the header. ; -; For each testcase, I use a CHECK-NEXT/NOT combo like an XFAIL with the -; granularity of a single check. If/when this behaviour is fixed, we'll know -; about it, and the test should be updated. +; In addition to loops, -block-freq has limited support for irreducible SCCs, +; which are SCCs with multiple entry blocks. Irreducible SCCs are discovered +; on they fly, and modelled as loops with multiple headers. +; +; The headers of irreducible sub-SCCs consist of its entry blocks and all nodes +; that are targets of a backedge within it (excluding backedges within true +; sub-loops). +; +; -block-freq is currently designed to act like a block is inserted that +; intercepts all the edges to the headers. All backedges and entries point to +; this block. Its successors are the headers, which split the frequency +; evenly. +; +; There are a number of testcases below. Only the first two have detailed +; explanations. ; ; Testcase #1 ; =========== @@ -77,36 +89,31 @@ return: ; loop as a whole is 1/4, so the loop scale should be 4. Summing c1 and c2 ; gives 28/7, or 4.0, which is nice confirmation of the math above. ; -; However, assuming c1 precedes c2 in reverse post-order, the current algorithm -; returns 3/4 and 13/16, respectively. LoopInfo ignores edges between loops -; (and doesn't see any loops here at all), and -block-freq ignores the -; irreducible edge from c2 to c1. -; +; -block-freq currently treats the two nodes as equals. +define void @multientry(i1 %x) { ; CHECK-LABEL: Printing analysis {{.*}} for function 'multientry': ; CHECK-NEXT: block-frequency-info: multientry -define void @multientry(i1 %x) { -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] entry: +; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] br i1 %x, label %c1, label %c2, !prof !2 -; This is like a single-line XFAIL (see above). -; CHECK-NEXT: c1: -; CHECK-NOT: float = 2.142857{{[0-9]*}}, c1: +; CHECK-NEXT: c1: float = 2.0, +; The "correct" answer is: float = 2.142857{{[0-9]*}}, br i1 %x, label %c2, label %exit, !prof !2 -; This is like a single-line XFAIL (see above). -; CHECK-NEXT: c2: -; CHECK-NOT: float = 1.857142{{[0-9]*}}, c2: +; CHECK-NEXT: c2: float = 2.0, +; The "correct" answer is: float = 1.857142{{[0-9]*}}, br i1 %x, label %c1, label %exit, !prof !2 -; We still shouldn't lose any frequency. -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] exit: +; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] ret void } +!2 = metadata !{metadata !"branch_weights", i32 3, i32 1} + ; Testcase #2 ; =========== ; @@ -124,73 +131,291 @@ exit: ; step, c1 and c2 each get 1/3 of what's left in c1 and c2 combined. This ; infinite series sums to 1. ; -; However, assuming c1 precedes c2 in reverse post-order, the current algorithm -; returns 1/2 and 3/4, respectively. LoopInfo ignores edges between loops (and -; treats c1 and c2 as self-loops only), and -block-freq ignores the irreducible -; edge from c2 to c1. -; -; Below I use a CHECK-NEXT/NOT combo like an XFAIL with the granularity of a -; single check. If/when this behaviour is fixed, we'll know about it, and the -; test should be updated. -; +; Since the currently algorithm *always* assumes entry blocks are equal, +; -block-freq gets the right answers here. +define void @crossloops(i2 %x) { ; CHECK-LABEL: Printing analysis {{.*}} for function 'crossloops': ; CHECK-NEXT: block-frequency-info: crossloops -define void @crossloops(i2 %x) { -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] entry: +; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] switch i2 %x, label %exit [ i2 1, label %c1 i2 2, label %c2 ], !prof !3 -; This is like a single-line XFAIL (see above). -; CHECK-NEXT: c1: -; CHECK-NOT: float = 1.0, c1: +; CHECK-NEXT: c1: float = 1.0, switch i2 %x, label %exit [ i2 1, label %c1 i2 2, label %c2 ], !prof !3 -; This is like a single-line XFAIL (see above). -; CHECK-NEXT: c2: -; CHECK-NOT: float = 1.0, c2: +; CHECK-NEXT: c2: float = 1.0, switch i2 %x, label %exit [ i2 1, label %c1 i2 2, label %c2 ], !prof !3 -; We still shouldn't lose any frequency. -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] exit: +; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] ret void } -!2 = metadata !{metadata !"branch_weights", i32 3, i32 1} !3 = metadata !{metadata !"branch_weights", i32 2, i32 2, i32 2} -; A reducible loop with irreducible control flow inside should still have -; correct exit frequency. -; +; A true loop with irreducible control flow inside. +define void @loop_around_irreducible(i1 %x) { ; CHECK-LABEL: Printing analysis {{.*}} for function 'loop_around_irreducible': ; CHECK-NEXT: block-frequency-info: loop_around_irreducible -define void @loop_around_irreducible(i1 %x) { +entry: +; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] + br label %loop + +loop: +; CHECK-NEXT: loop: float = 4.0, int = [[HEAD:[0-9]+]] + br i1 %x, label %left, label %right, !prof !4 + +left: +; CHECK-NEXT: left: float = 8.0, + br i1 %x, label %right, label %loop.end, !prof !5 + +right: +; CHECK-NEXT: right: float = 8.0, + br i1 %x, label %left, label %loop.end, !prof !5 + +loop.end: +; CHECK-NEXT: loop.end: float = 4.0, int = [[HEAD]] + br i1 %x, label %loop, label %exit, !prof !5 + +exit: +; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] + ret void +} +!4 = metadata !{metadata !"branch_weights", i32 1, i32 1} +!5 = metadata !{metadata !"branch_weights", i32 3, i32 1} + +; Two unrelated irreducible SCCs. +define void @two_sccs(i1 %x) { +; CHECK-LABEL: Printing analysis {{.*}} for function 'two_sccs': +; CHECK-NEXT: block-frequency-info: two_sccs +entry: +; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] + br i1 %x, label %a, label %b, !prof !6 + +a: +; CHECK-NEXT: a: float = 0.75, + br i1 %x, label %a.left, label %a.right, !prof !7 + +a.left: +; CHECK-NEXT: a.left: float = 1.5, + br i1 %x, label %a.right, label %exit, !prof !6 + +a.right: +; CHECK-NEXT: a.right: float = 1.5, + br i1 %x, label %a.left, label %exit, !prof !6 + +b: +; CHECK-NEXT: b: float = 0.25, + br i1 %x, label %b.left, label %b.right, !prof !7 + +b.left: +; CHECK-NEXT: b.left: float = 0.625, + br i1 %x, label %b.right, label %exit, !prof !8 + +b.right: +; CHECK-NEXT: b.right: float = 0.625, + br i1 %x, label %b.left, label %exit, !prof !8 + +exit: +; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] + ret void +} +!6 = metadata !{metadata !"branch_weights", i32 3, i32 1} +!7 = metadata !{metadata !"branch_weights", i32 1, i32 1} +!8 = metadata !{metadata !"branch_weights", i32 4, i32 1} + +; A true loop inside irreducible control flow. +define void @loop_inside_irreducible(i1 %x) { +; CHECK-LABEL: Printing analysis {{.*}} for function 'loop_inside_irreducible': +; CHECK-NEXT: block-frequency-info: loop_inside_irreducible +entry: +; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] + br i1 %x, label %left, label %right, !prof !9 + +left: +; CHECK-NEXT: left: float = 2.0, + br i1 %x, label %right, label %exit, !prof !10 + +right: +; CHECK-NEXT: right: float = 2.0, int = [[RIGHT:[0-9]+]] + br label %loop + +loop: +; CHECK-NEXT: loop: float = 6.0, + br i1 %x, label %loop, label %right.end, !prof !11 + +right.end: +; CHECK-NEXT: right.end: float = 2.0, int = [[RIGHT]] + br i1 %x, label %left, label %exit, !prof !10 + +exit: +; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] + ret void +} +!9 = metadata !{metadata !"branch_weights", i32 1, i32 1} +!10 = metadata !{metadata !"branch_weights", i32 3, i32 1} +!11 = metadata !{metadata !"branch_weights", i32 2, i32 1} + +; Irreducible control flow in a branch that's in a true loop. +define void @loop_around_branch_with_irreducible(i1 %x) { +; CHECK-LABEL: Printing analysis {{.*}} for function 'loop_around_branch_with_irreducible': +; CHECK-NEXT: block-frequency-info: loop_around_branch_with_irreducible +entry: ; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] + br label %loop + +loop: +; CHECK-NEXT: loop: float = 2.0, int = [[LOOP:[0-9]+]] + br i1 %x, label %normal, label %irreducible.entry, !prof !12 + +normal: +; CHECK-NEXT: normal: float = 1.5, + br label %loop.end + +irreducible.entry: +; CHECK-NEXT: irreducible.entry: float = 0.5, int = [[IRREDUCIBLE:[0-9]+]] + br i1 %x, label %left, label %right, !prof !13 + +left: +; CHECK-NEXT: left: float = 1.0, + br i1 %x, label %right, label %irreducible.exit, !prof !12 + +right: +; CHECK-NEXT: right: float = 1.0, + br i1 %x, label %left, label %irreducible.exit, !prof !12 + +irreducible.exit: +; CHECK-NEXT: irreducible.exit: float = 0.5, int = [[IRREDUCIBLE]] + br label %loop.end + +loop.end: +; CHECK-NEXT: loop.end: float = 2.0, int = [[LOOP]] + br i1 %x, label %loop, label %exit, !prof !13 + +exit: +; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] + ret void +} +!12 = metadata !{metadata !"branch_weights", i32 3, i32 1} +!13 = metadata !{metadata !"branch_weights", i32 1, i32 1} + +; Irreducible control flow between two true loops. +define void @loop_around_branch_with_irreducible_around_loop(i1 %x) { +; CHECK-LABEL: Printing analysis {{.*}} for function 'loop_around_branch_with_irreducible_around_loop': +; CHECK-NEXT: block-frequency-info: loop_around_branch_with_irreducible_around_loop entry: +; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] br label %loop -; CHECK-NEXT: loop: float = [[HEAD:[0-9.]+]], int = [[HEADINT:[0-9]+]] loop: - br i1 %x, label %left, label %right +; CHECK-NEXT: loop: float = 3.0, int = [[LOOP:[0-9]+]] + br i1 %x, label %normal, label %irreducible, !prof !14 + +normal: +; CHECK-NEXT: normal: float = 2.0, + br label %loop.end + +irreducible: +; CHECK-NEXT: irreducible: float = 1.0, + br i1 %x, label %left, label %right, !prof !15 -; CHECK-NEXT: left: left: - br i1 %x, label %right, label %loop.end +; CHECK-NEXT: left: float = 2.0, + br i1 %x, label %right, label %loop.end, !prof !16 -; CHECK-NEXT: right: right: - br i1 %x, label %left, label %loop.end +; CHECK-NEXT: right: float = 2.0, int = [[RIGHT:[0-9]+]] + br label %right.loop + +right.loop: +; CHECK-NEXT: right.loop: float = 10.0, + br i1 %x, label %right.loop, label %right.end, !prof !17 + +right.end: +; CHECK-NEXT: right.end: float = 2.0, int = [[RIGHT]] + br i1 %x, label %left, label %loop.end, !prof !16 -; CHECK-NEXT: loop.end: float = [[HEAD]], int = [[HEADINT]] loop.end: - br i1 %x, label %loop, label %exit +; CHECK-NEXT: loop.end: float = 3.0, int = [[LOOP]] + br i1 %x, label %loop, label %exit, !prof !14 + +exit: +; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] + ret void +} +!14 = metadata !{metadata !"branch_weights", i32 2, i32 1} +!15 = metadata !{metadata !"branch_weights", i32 1, i32 1} +!16 = metadata !{metadata !"branch_weights", i32 3, i32 1} +!17 = metadata !{metadata !"branch_weights", i32 4, i32 1} + +; An irreducible SCC with a non-header. +define void @nonheader(i1 %x) { +; CHECK-LABEL: Printing analysis {{.*}} for function 'nonheader': +; CHECK-NEXT: block-frequency-info: nonheader +entry: +; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] + br i1 %x, label %left, label %right, !prof !18 + +left: +; CHECK-NEXT: left: float = 1.0, + br i1 %x, label %bottom, label %exit, !prof !19 + +right: +; CHECK-NEXT: right: float = 1.0, + br i1 %x, label %bottom, label %exit, !prof !20 + +bottom: +; CHECK-NEXT: bottom: float = 1.0, + br i1 %x, label %left, label %right, !prof !18 -; CHECK-NEXT: float = 1.0, int = [[ENTRY]] exit: +; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] + ret void +} +!18 = metadata !{metadata !"branch_weights", i32 1, i32 1} +!19 = metadata !{metadata !"branch_weights", i32 1, i32 3} +!20 = metadata !{metadata !"branch_weights", i32 3, i32 1} + +; An irreducible SCC with an irreducible sub-SCC. In the current version of +; -block-freq, this means an extra header. +; +; This testcases uses non-trivial branch weights. The CHECK statements here +; will start to fail if we change -block-freq to be more accurate. Currently, +; we expect left, right and top to be treated as equal headers. +define void @nonentry_header(i1 %x, i2 %y) { +; CHECK-LABEL: Printing analysis {{.*}} for function 'nonentry_header': +; CHECK-NEXT: block-frequency-info: nonentry_header +entry: +; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] + br i1 %x, label %left, label %right, !prof !21 + +left: +; CHECK-NEXT: left: float = 3.0, + br i1 %x, label %top, label %bottom, !prof !22 + +right: +; CHECK-NEXT: right: float = 3.0, + br i1 %x, label %top, label %bottom, !prof !22 + +top: +; CHECK-NEXT: top: float = 3.0, + switch i2 %y, label %exit [ i2 0, label %left + i2 1, label %right + i2 2, label %bottom ], !prof !23 + +bottom: +; CHECK-NEXT: bottom: float = 4.5, + br label %top + +exit: +; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] ret void } +!21 = metadata !{metadata !"branch_weights", i32 2, i32 1} +!22 = metadata !{metadata !"branch_weights", i32 1, i32 1} +!23 = metadata !{metadata !"branch_weights", i32 8, i32 1, i32 3, i32 12} |
