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https://github.com/c64scene-ar/llvm-6502.git
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1f255419d4
that can be specialized by targets. The goal here is not to be more aggressive, but to just be more accurate with very obvious cases. There are instructions which are known to be truly free and which were not being modeled as such in this code -- see the regression test which is distilled from an inner loop of zlib. Everywhere the TTI cost model is insufficiently conservative I've added explicit checks with FIXME comments to go add proper modelling of these cost factors. If this causes regressions, the likely solution is to make TTI even more conservative in its cost estimates, but test cases will help here. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173342 91177308-0d34-0410-b5e6-96231b3b80d8
140 lines
3.6 KiB
LLVM
140 lines
3.6 KiB
LLVM
; RUN: opt < %s -simplifycfg -phi-node-folding-threshold=2 -S | FileCheck %s
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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-n8:16:32:64-S128"
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target triple = "x86_64-unknown-linux-gnu"
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define i32 @test1(i32 %a, i32 %b, i32 %c) nounwind {
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; CHECK: @test1
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entry:
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%tmp1 = icmp eq i32 %b, 0
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br i1 %tmp1, label %bb1, label %bb3
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bb1: ; preds = %entry
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%tmp2 = icmp sgt i32 %c, 1
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br i1 %tmp2, label %bb2, label %bb3
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; CHECK: bb1:
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; CHECK-NEXT: icmp sgt i32 %c, 1
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; CHECK-NEXT: add i32 %a, 1
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; CHECK-NEXT: select i1 %tmp2, i32 %tmp3, i32 %a
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; CHECK-NEXT: br label %bb3
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bb2: ; preds = bb1
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%tmp3 = add i32 %a, 1
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br label %bb3
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bb3: ; preds = %bb2, %entry
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%tmp4 = phi i32 [ %b, %entry ], [ %a, %bb1 ], [ %tmp3, %bb2 ]
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%tmp5 = sub i32 %tmp4, 1
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ret i32 %tmp5
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}
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declare i8 @llvm.cttz.i8(i8, i1)
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define i8 @test2(i8 %a) {
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; CHECK: @test2
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br i1 undef, label %bb_true, label %bb_false
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bb_true:
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%b = tail call i8 @llvm.cttz.i8(i8 %a, i1 false)
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br label %join
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bb_false:
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br label %join
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join:
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%c = phi i8 [%b, %bb_true], [%a, %bb_false]
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; CHECK: select
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ret i8 %c
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}
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define i8* @test3(i1* %dummy, i8* %a, i8* %b) {
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; Test that a weird, unfolded constant cast in the PHI don't block speculation.
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; CHECK: @test3
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entry:
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%cond1 = load volatile i1* %dummy
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br i1 %cond1, label %if, label %end
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if:
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%cond2 = load volatile i1* %dummy
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br i1 %cond2, label %then, label %end
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then:
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br label %end
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end:
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%x = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 42 to i8*), %then ]
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; CHECK-NOT: phi
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; CHECK: select i1 %cond2, i8* inttoptr
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ret i8* %x
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}
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define i8* @test4(i1* %dummy, i8* %a, i8* %b) {
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; Test that we don't speculate an arbitrarily large number of unfolded constant
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; expressions.
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; CHECK: @test4
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entry:
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%cond1 = load volatile i1* %dummy
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br i1 %cond1, label %if, label %end
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if:
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%cond2 = load volatile i1* %dummy
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br i1 %cond2, label %then, label %end
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then:
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br label %end
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end:
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%x1 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 1 to i8*), %then ]
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%x2 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 2 to i8*), %then ]
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%x3 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 3 to i8*), %then ]
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%x4 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 4 to i8*), %then ]
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%x5 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 5 to i8*), %then ]
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%x6 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 6 to i8*), %then ]
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%x7 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 7 to i8*), %then ]
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%x8 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 8 to i8*), %then ]
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%x9 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 9 to i8*), %then ]
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%x10 = phi i8* [ %a, %entry ], [ %b, %if ], [ inttoptr (i64 10 to i8*), %then ]
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; CHECK-NOT: select
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; CHECK: phi i8*
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; CHECK: phi i8*
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; CHECK: phi i8*
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; CHECK: phi i8*
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; CHECK: phi i8*
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; CHECK: phi i8*
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; CHECK: phi i8*
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; CHECK: phi i8*
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; CHECK: phi i8*
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; CHECK: phi i8*
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ret i8* %x10
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}
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define i16 @test5(i1* %dummy, i16 %a, i16 %b) {
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; Test that we speculate no-op instructions.
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; CHECK: @test5
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entry:
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%cond1 = load volatile i1* %dummy
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br i1 %cond1, label %if, label %end
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if:
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%cond2 = load volatile i1* %dummy
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%a.conv = sext i16 %a to i32
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%b.conv = sext i16 %b to i32
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%cmp = icmp ult i32 %a.conv, %b.conv
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br i1 %cond2, label %then, label %end
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then:
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%sub = sub i32 %a.conv, %b.conv
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%sub.conv = trunc i32 %sub to i16
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br label %end
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end:
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%x = phi i16 [ %a, %entry ], [ %b, %if ], [ %sub.conv, %then ]
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; CHECK-NOT: phi
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; CHECK: select i1
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ret i16 %x
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}
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