[StructurizeCFG] nested-if zerocost hoist bugfix (#155408)
When zero cost instructions are hoisted, the simplifyHoistedPhi function
was setting incoming phi values which were not dominating the use
causing runtime failure. This was set to poison by rebuildSSA function.
This commit fixes the issue.
diff --git a/llvm/lib/Transforms/Scalar/StructurizeCFG.cpp b/llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
index bb7dbc2..e056253 100644
--- a/llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
+++ b/llvm/lib/Transforms/Scalar/StructurizeCFG.cpp
@@ -997,7 +997,8 @@
continue;
OtherPhi->setIncomingValue(PoisonValBBIdx, V);
- Phi->setIncomingValue(i, OtherV);
+ if (DT->dominates(OtherV, Phi))
+ Phi->setIncomingValue(i, OtherV);
}
}
}
diff --git a/llvm/test/CodeGen/AMDGPU/structurize-hoist.ll b/llvm/test/CodeGen/AMDGPU/structurize-hoist.ll
index 8b6e5eb..b403651 100644
--- a/llvm/test/CodeGen/AMDGPU/structurize-hoist.ll
+++ b/llvm/test/CodeGen/AMDGPU/structurize-hoist.ll
@@ -189,12 +189,11 @@
; GFX900-NEXT: s_mov_b64 s[10:11], -1
; GFX900-NEXT: s_xor_b64 s[4:5], s[6:7], -1
; GFX900-NEXT: s_mov_b64 s[12:13], s[6:7]
-; GFX900-NEXT: ; implicit-def: $vgpr3
+; GFX900-NEXT: s_waitcnt vmcnt(0) lgkmcnt(0)
+; GFX900-NEXT: v_mov_b32_e32 v3, v4
; GFX900-NEXT: s_and_saveexec_b64 s[8:9], s[4:5]
; GFX900-NEXT: s_cbranch_execz .LBB3_4
; GFX900-NEXT: ; %bb.1: ; %if
-; GFX900-NEXT: s_waitcnt vmcnt(0) lgkmcnt(0)
-; GFX900-NEXT: v_mov_b32_e32 v3, v4
; GFX900-NEXT: s_and_saveexec_b64 s[12:13], s[4:5]
; GFX900-NEXT: s_cbranch_execz .LBB3_3
; GFX900-NEXT: ; %bb.2: ; %if_2
@@ -230,7 +229,6 @@
; GFX900-NEXT: s_or_b64 exec, exec, s[8:9]
; GFX900-NEXT: s_and_saveexec_b64 s[6:7], s[4:5]
; GFX900-NEXT: s_or_b64 exec, exec, s[6:7]
-; GFX900-NEXT: s_waitcnt vmcnt(0) lgkmcnt(0)
; GFX900-NEXT: flat_store_dword v[0:1], v4
; GFX900-NEXT: s_waitcnt vmcnt(0) lgkmcnt(0)
; GFX900-NEXT: s_setpc_b64 s[30:31]
diff --git a/llvm/test/Transforms/StructurizeCFG/hoist-zerocost.ll b/llvm/test/Transforms/StructurizeCFG/hoist-zerocost.ll
index 71de4f4..d084e19 100644
--- a/llvm/test/Transforms/StructurizeCFG/hoist-zerocost.ll
+++ b/llvm/test/Transforms/StructurizeCFG/hoist-zerocost.ll
@@ -172,7 +172,7 @@
; CHECK-NEXT: [[A16:%.*]] = icmp slt i32 [[VAL]], 255
; CHECK-NEXT: br i1 [[COND_INV]], label %[[THEN_2:.*]], label %[[FLOW1:.*]]
; CHECK: [[FLOW]]:
-; CHECK-NEXT: [[TMP0:%.*]] = phi i32 [ [[TMP2:%.*]], %[[FLOW1]] ], [ poison, %[[ENTRY]] ]
+; CHECK-NEXT: [[TMP0:%.*]] = phi i32 [ [[TMP2:%.*]], %[[FLOW1]] ], [ [[A_ELSE]], %[[ENTRY]] ]
; CHECK-NEXT: [[TMP1:%.*]] = phi i1 [ [[TMP3:%.*]], %[[FLOW1]] ], [ [[COND]], %[[ENTRY]] ]
; CHECK-NEXT: br i1 [[TMP1]], label %[[ELSE:.*]], label %[[MERGE:.*]]
; CHECK: [[THEN_2]]:
