c9325f8a2e
Right now the algorithm does not exit on unpredictable values. It waits until all the paths have been enumerated to see if any of those paths have that value. Waiting this late leads to a lot of wasteful computation and higher compile time. In this patch I have added a heuristic that checks if the value comes from the same inner loops as the switch, if so, then it is likely that the value will also be seen on a threadable path and the code in `getStateDefMap()` return an empty map. I tested this on the llvm test suite and the only change in the number of threaded switches was in 7zip (before 23, after 18). In all of those cases the current algorithm was partially threading the loop because it was hitting a limit on the number of paths to be explored. On increasing this limit even the current algorithm finds paths where the unpredictable value is seen. Compile time(with pass enabled by default and this patch): https://llvm-compile-time-tracker.com/compare.php?from=8c5e9cf737138aba22a4a8f64ef2c5efc80dd7f9&to=42c75d888058b35c6d15901b34e36251d8f766b9&stat=instructions:u
125 lines
4.3 KiB
LLVM
125 lines
4.3 KiB
LLVM
; REQUIRES: asserts
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; RUN: opt -S -passes=dfa-jump-threading %s -debug-only=dfa-jump-threading 2>&1 | FileCheck %s
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; CHECK-COUNT-3: Exiting early due to unpredictability heuristic.
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@.str.1 = private unnamed_addr constant [3 x i8] c"10\00", align 1
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@.str.2 = private unnamed_addr constant [3 x i8] c"30\00", align 1
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@.str.3 = private unnamed_addr constant [3 x i8] c"20\00", align 1
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@.str.4 = private unnamed_addr constant [3 x i8] c"40\00", align 1
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define void @test1(i32 noundef %num, i32 noundef %num2) {
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entry:
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br label %while.body
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while.body: ; preds = %entry, %sw.epilog
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%num.addr.0 = phi i32 [ %num, %entry ], [ %num.addr.1, %sw.epilog ]
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switch i32 %num.addr.0, label %sw.default [
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i32 10, label %sw.bb
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i32 30, label %sw.bb1
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i32 20, label %sw.bb2
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i32 40, label %sw.bb3
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]
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sw.bb: ; preds = %while.body
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%call.i = tail call i32 @bar(ptr noundef nonnull @.str.1)
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br label %sw.epilog
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sw.bb1: ; preds = %while.body
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%call.i4 = tail call i32 @bar(ptr noundef nonnull @.str.2)
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br label %sw.epilog
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sw.bb2: ; preds = %while.body
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%call.i5 = tail call i32 @bar(ptr noundef nonnull @.str.3)
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br label %sw.epilog
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sw.bb3: ; preds = %while.body
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%call.i6 = tail call i32 @bar(ptr noundef nonnull @.str.4)
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%call = tail call noundef i32 @foo()
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%add = add nsw i32 %call, %num2
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br label %sw.epilog
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sw.default: ; preds = %while.body
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ret void
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sw.epilog: ; preds = %sw.bb3, %sw.bb2, %sw.bb1, %sw.bb
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%num.addr.1 = phi i32 [ %add, %sw.bb3 ], [ 40, %sw.bb2 ], [ 20, %sw.bb1 ], [ 30, %sw.bb ]
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br label %while.body
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}
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define void @test2(i32 noundef %num, i32 noundef %num2) {
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entry:
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br label %while.body
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while.body: ; preds = %entry, %sw.epilog
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%num.addr.0 = phi i32 [ %num, %entry ], [ %num.addr.1, %sw.epilog ]
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switch i32 %num.addr.0, label %sw.default [
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i32 10, label %sw.epilog
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i32 30, label %sw.bb1
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i32 20, label %sw.bb2
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i32 40, label %sw.bb3
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]
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sw.bb1: ; preds = %while.body
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br label %sw.epilog
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sw.bb2: ; preds = %while.body
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br label %sw.epilog
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sw.bb3: ; preds = %while.body
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br label %sw.epilog
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sw.default: ; preds = %while.body
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ret void
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sw.epilog: ; preds = %while.body, %sw.bb3, %sw.bb2, %sw.bb1
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%.str.4.sink = phi ptr [ @.str.4, %sw.bb3 ], [ @.str.3, %sw.bb2 ], [ @.str.2, %sw.bb1 ], [ @.str.1, %while.body ]
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%num.addr.1 = phi i32 [ %num2, %sw.bb3 ], [ 40, %sw.bb2 ], [ 20, %sw.bb1 ], [ 30, %while.body ]
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%call.i6 = tail call i32 @bar(ptr noundef nonnull %.str.4.sink)
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br label %while.body
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}
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define void @test3(i32 noundef %num, i32 noundef %num2) {
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entry:
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%add = add nsw i32 %num2, 40
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br label %while.body
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while.body: ; preds = %entry, %sw.epilog
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%num.addr.0 = phi i32 [ %num, %entry ], [ %num.addr.1, %sw.epilog ]
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switch i32 %num.addr.0, label %sw.default [
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i32 10, label %sw.bb
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i32 30, label %sw.bb1
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i32 20, label %sw.bb2
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i32 40, label %sw.bb3
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]
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sw.bb: ; preds = %while.body
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%call.i = tail call i32 @bar(ptr noundef nonnull @.str.1)
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br label %sw.epilog
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sw.bb1: ; preds = %while.body
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%call.i5 = tail call i32 @bar(ptr noundef nonnull @.str.2)
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br label %sw.epilog
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sw.bb2: ; preds = %while.body
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%call.i6 = tail call i32 @bar(ptr noundef nonnull @.str.3)
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br label %sw.epilog
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sw.bb3: ; preds = %while.body
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%call.i7 = tail call i32 @bar(ptr noundef nonnull @.str.4)
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br label %sw.epilog
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sw.default: ; preds = %while.body
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ret void
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sw.epilog: ; preds = %sw.bb3, %sw.bb2, %sw.bb1, %sw.bb
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%num.addr.1 = phi i32 [ %add, %sw.bb3 ], [ 40, %sw.bb2 ], [ 20, %sw.bb1 ], [ 30, %sw.bb ]
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br label %while.body
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}
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declare noundef i32 @foo()
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declare noundef i32 @bar(ptr nocapture noundef readonly)
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