From 687b92cd9cf58e3405b906c7accd13bbdb813793 Mon Sep 17 00:00:00 2001 From: Nikita Popov Date: Sun, 2 Dec 2018 14:14:11 +0000 Subject: [ValueTracking] Support funnel shifts in computeKnownBits() If the shift amount is known, we can determine the known bits of the output based on the known bits of two inputs. This is essentially the same functionality as implemented in D54869, but for ValueTracking rather than InstCombine SimplifyDemandedBits. Differential Revision: https://reviews.llvm.org/D55140 llvm-svn: 348091 --- llvm/unittests/Analysis/ValueTrackingTest.cpp | 48 +++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) (limited to 'llvm/unittests/Analysis/ValueTrackingTest.cpp') diff --git a/llvm/unittests/Analysis/ValueTrackingTest.cpp b/llvm/unittests/Analysis/ValueTrackingTest.cpp index eeefb605867..5b36d63b390 100644 --- a/llvm/unittests/Analysis/ValueTrackingTest.cpp +++ b/llvm/unittests/Analysis/ValueTrackingTest.cpp @@ -568,3 +568,51 @@ TEST_F(ComputeKnownBitsTest, ComputeKnownMulBits) { "}\n"); expectKnownBits(/*zero*/ 95u, /*one*/ 32u); } + +TEST_F(ComputeKnownBitsTest, ComputeKnownFshl) { + // fshl(....1111....0000, 00..1111........, 6) + // = 11....000000..11 + parseAssembly( + "define i16 @test(i16 %a, i16 %b) {\n" + " %aa = shl i16 %a, 4\n" + " %bb = lshr i16 %b, 2\n" + " %aaa = or i16 %aa, 3840\n" + " %bbb = or i16 %bb, 3840\n" + " %A = call i16 @llvm.fshl.i16(i16 %aaa, i16 %bbb, i16 6)\n" + " ret i16 %A\n" + "}\n" + "declare i16 @llvm.fshl.i16(i16, i16, i16)\n"); + expectKnownBits(/*zero*/ 1008u, /*one*/ 49155u); +} + +TEST_F(ComputeKnownBitsTest, ComputeKnownFshr) { + // fshr(....1111....0000, 00..1111........, 26) + // = 11....000000..11 + parseAssembly( + "define i16 @test(i16 %a, i16 %b) {\n" + " %aa = shl i16 %a, 4\n" + " %bb = lshr i16 %b, 2\n" + " %aaa = or i16 %aa, 3840\n" + " %bbb = or i16 %bb, 3840\n" + " %A = call i16 @llvm.fshr.i16(i16 %aaa, i16 %bbb, i16 26)\n" + " ret i16 %A\n" + "}\n" + "declare i16 @llvm.fshr.i16(i16, i16, i16)\n"); + expectKnownBits(/*zero*/ 1008u, /*one*/ 49155u); +} + +TEST_F(ComputeKnownBitsTest, ComputeKnownFshlZero) { + // fshl(....1111....0000, 00..1111........, 0) + // = ....1111....0000 + parseAssembly( + "define i16 @test(i16 %a, i16 %b) {\n" + " %aa = shl i16 %a, 4\n" + " %bb = lshr i16 %b, 2\n" + " %aaa = or i16 %aa, 3840\n" + " %bbb = or i16 %bb, 3840\n" + " %A = call i16 @llvm.fshl.i16(i16 %aaa, i16 %bbb, i16 0)\n" + " ret i16 %A\n" + "}\n" + "declare i16 @llvm.fshl.i16(i16, i16, i16)\n"); + expectKnownBits(/*zero*/ 15u, /*one*/ 3840u); +} -- cgit v1.2.3