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Diffstat (limited to 'test/Analysis/BlockFrequencyInfo/irreducible.ll')
-rw-r--r-- | test/Analysis/BlockFrequencyInfo/irreducible.ll | 197 |
1 files changed, 0 insertions, 197 deletions
diff --git a/test/Analysis/BlockFrequencyInfo/irreducible.ll b/test/Analysis/BlockFrequencyInfo/irreducible.ll deleted file mode 100644 index 46a2958700..0000000000 --- a/test/Analysis/BlockFrequencyInfo/irreducible.ll +++ /dev/null @@ -1,197 +0,0 @@ -; RUN: opt < %s -analyze -block-freq | FileCheck %s - -; A loop with multiple exits should be handled correctly. -; -; CHECK-LABEL: Printing analysis {{.*}} for function 'multiexit': -; CHECK-NEXT: block-frequency-info: multiexit -define void @multiexit(i32 %a) { -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] -entry: - br label %loop.1 - -; CHECK-NEXT: loop.1: float = 1.333{{3*}}, -loop.1: - %i = phi i32 [ 0, %entry ], [ %inc.2, %loop.2 ] - call void @f(i32 %i) - %inc.1 = add i32 %i, 1 - %cmp.1 = icmp ugt i32 %inc.1, %a - br i1 %cmp.1, label %exit.1, label %loop.2, !prof !0 - -; CHECK-NEXT: loop.2: float = 0.666{{6*7}}, -loop.2: - call void @g(i32 %inc.1) - %inc.2 = add i32 %inc.1, 1 - %cmp.2 = icmp ugt i32 %inc.2, %a - br i1 %cmp.2, label %exit.2, label %loop.1, !prof !1 - -; CHECK-NEXT: exit.1: float = 0.666{{6*7}}, -exit.1: - call void @h(i32 %inc.1) - br label %return - -; CHECK-NEXT: exit.2: float = 0.333{{3*}}, -exit.2: - call void @i(i32 %inc.2) - br label %return - -; CHECK-NEXT: return: float = 1.0, int = [[ENTRY]] -return: - ret void -} - -declare void @f(i32 %x) -declare void @g(i32 %x) -declare void @h(i32 %x) -declare void @i(i32 %x) - -!0 = metadata !{metadata !"branch_weights", i32 3, i32 3} -!1 = metadata !{metadata !"branch_weights", i32 5, i32 5} - -; 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. -; -; There are two testcases below. -; -; 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. -; -; Testcase #1 -; =========== -; -; In this case c1 and c2 should have frequencies of 15/7 and 13/7, -; respectively. To calculate this, consider assigning 1.0 to entry, and -; distributing frequency iteratively (to infinity). At the first iteration, -; entry gives 3/4 to c1 and 1/4 to c2. At every step after, c1 and c2 give 3/4 -; of what they have to each other. Somehow, all of it comes out to exit. -; -; c1 = 3/4 + 1/4*3/4 + 3/4*3^2/4^2 + 1/4*3^3/4^3 + 3/4*3^3/4^3 + ... -; c2 = 1/4 + 3/4*3/4 + 1/4*3^2/4^2 + 3/4*3^3/4^3 + 1/4*3^3/4^3 + ... -; -; Simplify by splitting up the odd and even terms of the series and taking out -; factors so that the infite series matches: -; -; c1 = 3/4 *(9^0/16^0 + 9^1/16^1 + 9^2/16^2 + ...) -; + 3/16*(9^0/16^0 + 9^1/16^1 + 9^2/16^2 + ...) -; c2 = 1/4 *(9^0/16^0 + 9^1/16^1 + 9^2/16^2 + ...) -; + 9/16*(9^0/16^0 + 9^1/16^1 + 9^2/16^2 + ...) -; -; c1 = 15/16*(9^0/16^0 + 9^1/16^1 + 9^2/16^2 + ...) -; c2 = 13/16*(9^0/16^0 + 9^1/16^1 + 9^2/16^2 + ...) -; -; Since this geometric series sums to 16/7: -; -; c1 = 15/7 -; c2 = 13/7 -; -; If we treat c1 and c2 as members of the same loop, the exit frequency of the -; 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. -; -; CHECK-LABEL: Printing analysis {{.*}} for function 'multientry': -; CHECK-NEXT: block-frequency-info: multientry -define void @multientry(i32 %a) { -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] -entry: - %choose = call i32 @choose(i32 %a) - %compare = icmp ugt i32 %choose, %a - br i1 %compare, 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: - %i1 = phi i32 [ %a, %entry ], [ %i2.inc, %c2 ] - %i1.inc = add i32 %i1, 1 - %choose1 = call i32 @choose(i32 %i1) - %compare1 = icmp ugt i32 %choose1, %a - br i1 %compare1, 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: - %i2 = phi i32 [ %a, %entry ], [ %i1.inc, %c1 ] - %i2.inc = add i32 %i2, 1 - %choose2 = call i32 @choose(i32 %i2) - %compare2 = icmp ugt i32 %choose2, %a - br i1 %compare2, label %c1, label %exit, !prof !2 - -; We still shouldn't lose any frequency. -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] -exit: - ret void -} - -; Testcase #2 -; =========== -; -; In this case c1 and c2 should be treated as equals in a single loop. The -; exit frequency is 1/3, so the scaling factor for the loop should be 3.0. The -; loop is entered 2/3 of the time, and c1 and c2 split the total loop frequency -; evenly (1/2), so they should each have frequencies of 1.0 (3.0*2/3*1/2). -; Another way of computing this result is by assigning 1.0 to entry and showing -; that c1 and c2 should accumulate frequencies of: -; -; 1/3 + 2/9 + 4/27 + 8/81 + ... -; 2^0/3^1 + 2^1/3^2 + 2^2/3^3 + 2^3/3^4 + ... -; -; At the first step, c1 and c2 each get 1/3 of the entry. At each subsequent -; 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. -; -; CHECK-LABEL: Printing analysis {{.*}} for function 'crossloops': -; CHECK-NEXT: block-frequency-info: crossloops -define void @crossloops(i32 %a) { -; CHECK-NEXT: entry: float = 1.0, int = [[ENTRY:[0-9]+]] -entry: - %choose = call i32 @choose(i32 %a) - switch i32 %choose, label %exit [ i32 1, label %c1 - i32 2, label %c2 ], !prof !3 - -; This is like a single-line XFAIL (see above). -; CHECK-NEXT: c1: -; CHECK-NOT: float = 1.0, -c1: - %i1 = phi i32 [ %a, %entry ], [ %i1.inc, %c1 ], [ %i2.inc, %c2 ] - %i1.inc = add i32 %i1, 1 - %choose1 = call i32 @choose(i32 %i1) - switch i32 %choose1, label %exit [ i32 1, label %c1 - i32 2, label %c2 ], !prof !3 - -; This is like a single-line XFAIL (see above). -; CHECK-NEXT: c2: -; CHECK-NOT: float = 1.0, -c2: - %i2 = phi i32 [ %a, %entry ], [ %i1.inc, %c1 ], [ %i2.inc, %c2 ] - %i2.inc = add i32 %i2, 1 - %choose2 = call i32 @choose(i32 %i2) - switch i32 %choose2, label %exit [ i32 1, label %c1 - i32 2, label %c2 ], !prof !3 - -; We still shouldn't lose any frequency. -; CHECK-NEXT: exit: float = 1.0, int = [[ENTRY]] -exit: - ret void -} - -declare i32 @choose(i32) - -!2 = metadata !{metadata !"branch_weights", i32 3, i32 1} -!3 = metadata !{metadata !"branch_weights", i32 2, i32 2, i32 2} |