[llvm] [RISCV] Update the latency of floating point load in SiFive P500 scheduling model (PR #133165)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-risc-v

Author: Min-Yih Hsu (mshockwave)

<details>
<summary>Changes</summary>

P500-series cores should have a floating point load latency closer to 5 cycles, just like P400- and P600-series cores.

---
Full diff: https://github.com/llvm/llvm-project/pull/133165.diff


2 Files Affected:

- (modified) llvm/lib/Target/RISCV/RISCVSchedSiFiveP500.td (+1-1) 
- (modified) llvm/test/tools/llvm-mca/RISCV/SiFiveP500/load.s (+5-5) 


``````````diff
diff --git a/llvm/lib/Target/RISCV/RISCVSchedSiFiveP500.td b/llvm/lib/Target/RISCV/RISCVSchedSiFiveP500.td
index 32cfa701c4fdb..ca116e0c54f3f 100644
--- a/llvm/lib/Target/RISCV/RISCVSchedSiFiveP500.td
+++ b/llvm/lib/Target/RISCV/RISCVSchedSiFiveP500.td
@@ -132,7 +132,7 @@ def : WriteRes<WriteLDW, [SiFiveP500Load]>;
 def : WriteRes<WriteLDD, [SiFiveP500Load]>;
 }
 
-let Latency = 6 in {
+let Latency = 5 in {
 def : WriteRes<WriteFLD16, [SiFiveP500Load]>;
 def : WriteRes<WriteFLD32, [SiFiveP500Load]>;
 def : WriteRes<WriteFLD64, [SiFiveP500Load]>;
diff --git a/llvm/test/tools/llvm-mca/RISCV/SiFiveP500/load.s b/llvm/test/tools/llvm-mca/RISCV/SiFiveP500/load.s
index 2b7df9215e0cb..133d7ce4d626d 100644
--- a/llvm/test/tools/llvm-mca/RISCV/SiFiveP500/load.s
+++ b/llvm/test/tools/llvm-mca/RISCV/SiFiveP500/load.s
@@ -9,12 +9,12 @@ fld ft0, 0(a0)
 
 # CHECK:      Iterations:        1
 # CHECK-NEXT: Instructions:      4
-# CHECK-NEXT: Total Cycles:      12
+# CHECK-NEXT: Total Cycles:      11
 # CHECK-NEXT: Total uOps:        4
 
 # CHECK:      Dispatch Width:    3
-# CHECK-NEXT: uOps Per Cycle:    0.33
-# CHECK-NEXT: IPC:               0.33
+# CHECK-NEXT: uOps Per Cycle:    0.36
+# CHECK-NEXT: IPC:               0.36
 # CHECK-NEXT: Block RThroughput: 4.0
 
 # CHECK:      Instruction Info:
@@ -28,8 +28,8 @@ fld ft0, 0(a0)
 # CHECK:      [1]    [2]    [3]    [4]    [5]    [6]    Instructions:
 # CHECK-NEXT:  1      4     1.00    *                   lw	t0, 0(a0)
 # CHECK-NEXT:  1      4     1.00    *                   ld	t0, 0(a0)
-# CHECK-NEXT:  1      6     1.00    *                   flw	ft0, 0(a0)
-# CHECK-NEXT:  1      6     1.00    *                   fld	ft0, 0(a0)
+# CHECK-NEXT:  1      5     1.00    *                   flw	ft0, 0(a0)
+# CHECK-NEXT:  1      5     1.00    *                   fld	ft0, 0(a0)
 
 # CHECK:      Resources:
 # CHECK-NEXT: [0]   - SiFiveP500Div

``````````

</details>


https://github.com/llvm/llvm-project/pull/133165