[llvm] 571d151 - [RISCV][MISched] Set EnableIntervals to true for SiFive7 (#75681)

[via llvm-commits]

Author: Michael Maitland
Date: 2023-12-19T11:03:03-05:00
New Revision: 571d151deca57609fc08ee1721be51755a29870a

URL: https://github.com/llvm/llvm-project/commit/571d151deca57609fc08ee1721be51755a29870a
DIFF: https://github.com/llvm/llvm-project/commit/571d151deca57609fc08ee1721be51755a29870a.diff

LOG: [RISCV][MISched] Set EnableIntervals to true for SiFive7 (#75681)

The SiFive7 scheduler model has been using AcquireAtCycles and
ReleaseAtCycles for some time. Without EnableIntervals, the scheduler
was not making decisions based on this information. This patch sets
EnableIntervals to true, and the test case demonstrates that the VADD
instructions can be issued one cycle earlier since the VCQ is not
reserved. This leads to better saturation of the SiFive7VA.

Added: 
    llvm/test/CodeGen/RISCV/sifive7-enable-intervals.mir

Modified: 
    llvm/lib/Target/RISCV/RISCVSchedSiFive7.td

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/RISCV/RISCVSchedSiFive7.td b/llvm/lib/Target/RISCV/RISCVSchedSiFive7.td
index 45783d482f3bd7..f531ab2fac8f9f 100644
--- a/llvm/lib/Target/RISCV/RISCVSchedSiFive7.td
+++ b/llvm/lib/Target/RISCV/RISCVSchedSiFive7.td
@@ -198,6 +198,7 @@ def SiFive7Model : SchedMachineModel {
   let LoadLatency = 3;
   let MispredictPenalty = 3;
   let CompleteModel = 0;
+  let EnableIntervals = true;
   let UnsupportedFeatures = [HasStdExtZbkb, HasStdExtZbkc, HasStdExtZbkx,
                              HasStdExtZcmt, HasStdExtZknd, HasStdExtZkne,
                              HasStdExtZknh, HasStdExtZksed, HasStdExtZksh,

diff  --git a/llvm/test/CodeGen/RISCV/sifive7-enable-intervals.mir b/llvm/test/CodeGen/RISCV/sifive7-enable-intervals.mir
new file mode 100644
index 00000000000000..68e8c9e55ff3b8
--- /dev/null
+++ b/llvm/test/CodeGen/RISCV/sifive7-enable-intervals.mir
@@ -0,0 +1,56 @@
+# RUN: llc -mtriple=riscv64 -mcpu=sifive-x280 -run-pass=machine-scheduler      \
+# RUN:  -debug-only=machine-scheduler -misched-dump-schedule-trace             \
+# RUN:  -misched-topdown -o - %s 2>&1 | FileCheck %s
+
+# The purpose of this test is to show that the VADD instructions are issued so
+# that the SiFive7VA is saturated.
+---
+name:            add_m2
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    liveins: $v8m2, $v10m2, $v12m2, $v14m2, $x10
+
+    %4:gprnox0 = COPY $x10
+    %3:vrm2 = COPY $v14m2
+    %2:vrm2 = COPY $v12m2
+    %1:vrm2 = COPY $v10m2
+    %0:vrm2 = COPY $v8m2
+    dead $x0 = PseudoVSETVLI %4, 217 /* e64, m2, ta, ma */, implicit-def $vl, implicit-def $vtype
+    %5:vrm2 = PseudoVADD_VV_M2 undef %5, %0, %1, $noreg, 6 /* e64 */, 0 /* tu, mu */, implicit $vl, implicit $vtype
+    %6:vrm2 = PseudoVADD_VV_M2 undef %6, %3, %2, $noreg, 6 /* e64 */, 0 /* tu, mu */, implicit $vl, implicit $vtype
+    %7:vrm2 = PseudoVADD_VV_M2 undef %7, %5, %6, $noreg, 6 /* e64 */, 0 /* tu, mu */, implicit $vl, implicit $vtype
+    $v8m2 = COPY %7
+    PseudoRET implicit $v8m2
+
+# CHECK: *** Final schedule for %bb.0 ***
+# CHECK-NEXT:  * Schedule table (TopDown):
+# CHECK-NEXT:   i: issue
+# CHECK-NEXT:   x: resource booked
+# CHECK-NEXT: Cycle              | 0  | 1  | 2  | 3  | 4  | 5  | 6  | 7  | 8  | 9  | 10 | 11 | 12 | 13 | 14 | 15 | 16 |
+# CHECK-NEXT: SU(0)              | i  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:      SiFive7PipeAB | x  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT: SU(1)              | i  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:      SiFive7PipeAB | x  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT: SU(2)              |    | i  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:      SiFive7PipeAB |    | x  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT: SU(3)              |    | i  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:      SiFive7PipeAB |    | x  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT: SU(4)              |    |    | i  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:      SiFive7PipeAB |    |    | x  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT: SU(5)              |    |    | i  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:       SiFive7PipeA |    |    | x  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:      SiFive7PipeAB |    |    | x  |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT: SU(7)              |    |    |    |    | i  |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:         SiFive7VCQ |    |    |    |    | x  |    |    |    |    |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:          SiFive7VA |    |    |    |    |    | x  | x  | x  | x  |    |    |    |    |    |    |    |    |
+# CHECK-NEXT: SU(6)              |    |    |    |    |    |    |    |    | i  |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:         SiFive7VCQ |    |    |    |    |    |    |    |    | x  |    |    |    |    |    |    |    |    |
+# CHECK-NEXT:          SiFive7VA |    |    |    |    |    |    |    |    |    | x  | x  | x  | x  |    |    |    |    |
+# CHECK-NEXT: SU(8)              |    |    |    |    |    |    |    |    |    |    |    |    | i  |    |    |    |    |
+# CHECK-NEXT:         SiFive7VCQ |    |    |    |    |    |    |    |    |    |    |    |    | x  |    |    |    |    |
+# CHECK-NEXT:          SiFive7VA |    |    |    |    |    |    |    |    |    |    |    |    |    | x  | x  | x  | x  |
+# CHECK-NEXT: SU(9)              |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    | i  |
+# CHECK-NEXT:      SiFive7PipeAB |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    | x  |
+
+...