From 1f255419d424c85bc5dbb77f530561d46e5197cc Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Thu, 24 Jan 2013 12:39:29 +0000 Subject: Plug TTI into the speculation logic, giving it a real cost interface 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 --- test/Transforms/SimplifyCFG/SpeculativeExec.ll | 29 ++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) (limited to 'test/Transforms') diff --git a/test/Transforms/SimplifyCFG/SpeculativeExec.ll b/test/Transforms/SimplifyCFG/SpeculativeExec.ll index 7e27f415f7..bcef848040 100644 --- a/test/Transforms/SimplifyCFG/SpeculativeExec.ll +++ b/test/Transforms/SimplifyCFG/SpeculativeExec.ll @@ -108,3 +108,32 @@ end: ret i8* %x10 } + +define i16 @test5(i1* %dummy, i16 %a, i16 %b) { +; Test that we speculate no-op instructions. +; CHECK: @test5 + +entry: + %cond1 = load volatile i1* %dummy + br i1 %cond1, label %if, label %end + +if: + %cond2 = load volatile i1* %dummy + %a.conv = sext i16 %a to i32 + %b.conv = sext i16 %b to i32 + %cmp = icmp ult i32 %a.conv, %b.conv + br i1 %cond2, label %then, label %end + +then: + %sub = sub i32 %a.conv, %b.conv + %sub.conv = trunc i32 %sub to i16 + br label %end + +end: + %x = phi i16 [ %a, %entry ], [ %b, %if ], [ %sub.conv, %then ] +; CHECK-NOT: phi +; CHECK: select i1 + + ret i16 %x +} + -- cgit v1.2.3-18-g5258