7094c8deb2
Currently, `getExact` fails if it sees two exit counts in different blocks. There is
no solid reason to do so, given that we only calculate exact non-taken count
for exiting blocks that dominate latch. Using this fact, we can simply take min
out of all exits of all blocks to get the exact taken count.
This patch makes the calculation more optimistic with enforcing our assumption
with asserts. It allows us to calculate exact backedge taken count in trivial loops
like
for (int i = 0; i < 100; i++) {
if (i > 50) break;
. . .
}
Differential Revision: https://reviews.llvm.org/D44676
Reviewed By: fhahn
llvm-svn: 328611
48 lines
1.5 KiB
LLVM
48 lines
1.5 KiB
LLVM
; RUN: opt < %s -indvars -S | FileCheck %s
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;
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; This loop has multiple exits, and the value of %b1 depends on which
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; exit is taken. Indvars should correctly compute the exit values.
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;
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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"
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target triple = "x86_64-pc-linux-gnu"
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%struct..0anon = type <{ i8, [3 x i8] }>
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define i32 @main() nounwind {
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; CHECK-LABEL: @main(
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; CHECK: %b.1 = phi i32 [ 2, %bb ], [ 1, %bb2 ]
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entry:
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br label %bb2
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bb2: ; preds = %bb, %entry
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%sdata.0 = phi i32 [ 1, %entry ], [ %ins10, %bb ] ; <i32> [#uses=2]
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%b.0 = phi i32 [ 0, %entry ], [ %t0, %bb ] ; <i32> [#uses=2]
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%tmp6 = trunc i32 %sdata.0 to i8 ; <i8> [#uses=2]
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%t2 = and i8 %tmp6, 1 ; <i8> [#uses=1]
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%t3 = icmp eq i8 %t2, 0 ; <i1> [#uses=1]
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%t4 = xor i8 %tmp6, 1 ; <i8> [#uses=1]
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%tmp8 = zext i8 %t4 to i32 ; <i32> [#uses=1]
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%mask9 = and i32 %sdata.0, -256 ; <i32> [#uses=1]
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%ins10 = or i32 %tmp8, %mask9 ; <i32> [#uses=1]
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br i1 %t3, label %bb3, label %bb
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bb: ; preds = %bb2
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%t0 = add i32 %b.0, 1 ; <i32> [#uses=3]
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%t1 = icmp sgt i32 %t0, 100 ; <i1> [#uses=1]
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br i1 %t1, label %bb3, label %bb2
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bb3: ; preds = %bb, %bb2
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%b.1 = phi i32 [ %t0, %bb ], [ %b.0, %bb2 ] ; <i32> [#uses=1]
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%t5 = icmp eq i32 %b.1, 1 ; <i1> [#uses=1]
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br i1 %t5, label %bb5, label %bb4
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bb4: ; preds = %bb3
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tail call void @abort() noreturn nounwind
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unreachable
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bb5: ; preds = %bb3
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ret i32 0
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}
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declare void @abort() noreturn nounwind
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