[AMDGPU] Respect MBB alignment in the getFunctionCodeSize()

[rampitec]

No description provided.

[rampitec]

• [AMDGPU] Respect MBB alignment in the getFunctionCodeSize() #127142 👈 (View in Graphite)
• [AMDGPU] Early bail in getFunctionCodeSize for meta inst. NFC. #127129
• [AMDGPU] Move into SIProgramInfo and cache getFunctionCodeSize. NFCI. #127111 : 2 other dependent PRs (#126981 , #127246 )
• main

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[llvmbot]

@llvm/pr-subscribers-backend-amdgpu

Author: Stanislav Mekhanoshin (rampitec)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/127142.diff

2 Files Affected:

• (modified) llvm/lib/Target/AMDGPU/SIProgramInfo.cpp (+2)
• (modified) llvm/test/CodeGen/AMDGPU/code-size-estimate.mir (+89)

diff --git a/llvm/lib/Target/AMDGPU/SIProgramInfo.cpp b/llvm/lib/Target/AMDGPU/SIProgramInfo.cpp
index b995687e71780..9d9b4c83ac388 100644
--- a/llvm/lib/Target/AMDGPU/SIProgramInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIProgramInfo.cpp
@@ -212,6 +212,8 @@ uint64_t SIProgramInfo::getFunctionCodeSize(const MachineFunction &MF) {
   uint64_t CodeSize = 0;
 
   for (const MachineBasicBlock &MBB : MF) {
+    CodeSize = alignTo(CodeSize, MBB.getAlignment());
+
     for (const MachineInstr &MI : MBB) {
       // TODO: CodeSize should account for multiple functions.
 
diff --git a/llvm/test/CodeGen/AMDGPU/code-size-estimate.mir b/llvm/test/CodeGen/AMDGPU/code-size-estimate.mir
index 76eaf350301e4..9ae536af6f0e9 100644
--- a/llvm/test/CodeGen/AMDGPU/code-size-estimate.mir
+++ b/llvm/test/CodeGen/AMDGPU/code-size-estimate.mir
@@ -31,3 +31,92 @@ body:             |
 
   WAVE_BARRIER
 ...
+
+# CHECK: align4:                                 ; @align4
+# CHECK: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0) ; encoding: [0x00,0x00,0x8c,0xbf]
+# CHECK: s_cbranch_scc1 .LBB{{[0-9_]+}}          ; encoding: [A,A,0x85,0xbf]
+# CHECK: s_barrier                               ; encoding: [0x00,0x00,0x8a,0xbf]
+# CHECK: .p2align        2
+# CHECK: s_endpgm                                ; encoding: [0x00,0x00,0x81,0xbf]
+# CHECK: ; codeLenInByte = 16
+
+---
+name:            align4
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    $scc = IMPLICIT_DEF
+    S_CBRANCH_SCC1 %bb.2, implicit $scc
+
+  bb.1:
+    S_BARRIER
+
+  bb.2 (align 4):
+    S_ENDPGM 0
+...
+
+# CHECK: align8:                                 ; @align8
+# CHECK: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0) ; encoding: [0x00,0x00,0x8c,0xbf]
+# CHECK: s_cbranch_scc1 .LBB{{[0-9_]+}}          ; encoding: [A,A,0x85,0xbf]
+# CHECK: s_barrier                               ; encoding: [0x00,0x00,0x8a,0xbf]
+# CHECK: .p2align        3
+# CHECK: s_endpgm                                ; encoding: [0x00,0x00,0x81,0xbf]
+# CHECK: ; codeLenInByte = 20
+---
+name:            align8
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    $scc = IMPLICIT_DEF
+    S_CBRANCH_SCC1 %bb.2, implicit $scc
+
+  bb.1:
+    S_BARRIER
+
+  bb.2 (align 8):
+    S_ENDPGM 0
+...
+
+# CHECK: align16:                                ; @align16
+# CHECK: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0) ; encoding: [0x00,0x00,0x8c,0xbf]
+# CHECK: s_cbranch_scc1 .LBB{{[0-9_]+}}          ; encoding: [A,A,0x85,0xbf]
+# CHECK: s_barrier                               ; encoding: [0x00,0x00,0x8a,0xbf]
+# CHECK: .p2align        4
+# CHECK: s_endpgm                                ; encoding: [0x00,0x00,0x81,0xbf]
+# CHECK: ; codeLenInByte = 20
+---
+name:            align16
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    $scc = IMPLICIT_DEF
+    S_CBRANCH_SCC1 %bb.2, implicit $scc
+
+  bb.1:
+    S_BARRIER
+
+  bb.2 (align 16):
+    S_ENDPGM 0
+...
+
+# CHECK: align32:                                ; @align32
+# CHECK: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0) ; encoding: [0x00,0x00,0x8c,0xbf]
+# CHECK: s_cbranch_scc1 .LBB{{[0-9_]+}}          ; encoding: [A,A,0x85,0xbf]
+# CHECK: s_barrier                               ; encoding: [0x00,0x00,0x8a,0xbf]
+# CHECK: .p2align        5
+# CHECK: s_endpgm                                ; encoding: [0x00,0x00,0x81,0xbf]
+# CHECK: ; codeLenInByte = 36
+---
+name:            align32
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    $scc = IMPLICIT_DEF
+    S_CBRANCH_SCC1 %bb.2, implicit $scc
+
+  bb.1:
+    S_BARRIER
+
+  bb.2 (align 32):
+    S_ENDPGM 0
+...

[rampitec]

Which one do you prefer, this or #127246? They are mutually exclusive.

[arsenm]

Which one do you prefer, this or #127246? They are mutually exclusive.

They're not really. This one is the incremental step which adds the test, #127246 is the final form

[rampitec]

Which one do you prefer, this or #127246? They are mutually exclusive.

They're not really. This one is the incremental step which adds the test, #127246 is the final form

The test is meaningless if we overestimate. I.e., I have carefully set the margins in the test. If we go 'full align - 1' it does not make any sense to do it.

[rampitec]

And in any case it is a moot until baseline change is accepted.