[AMDGPU] Fix handling of FP in cs.chain functions #161194
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In case there is an dynamic alloca / an alloca which is not in the entry block, cs.chain functions do not set up an FP, but are reported to need one. This results in a failed assertion in `SIFrameLowering::emitPrologue()` (Assertion `(!HasFP || FPSaved) && "Needed to save FP but didn't save it anywhere"' failed.) This commit changes `hasFPImpl` so that the need for an SP in a cs.chain function does not directly imply the need for an FP anymore. This LLVM defect was identified via the AMD Fuzzing project.
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@llvm/pr-subscribers-backend-amdgpu Author: Robert Imschweiler (ro-i) ChangesIn case there is an dynamic alloca / an alloca which is not in the entry block, cs.chain functions do not set up an FP, but are reported to need one. This results in a failed assertion in This LLVM defect was identified via the AMD Fuzzing project. Re-opens #132711 Full diff: https://github.com/llvm/llvm-project/pull/161194.diff 2 Files Affected:
diff --git a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
index 7c5d4fc2dacf6..7c2ce2737f7be 100644
--- a/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
@@ -2166,7 +2166,9 @@ bool SIFrameLowering::hasFPImpl(const MachineFunction &MF) const {
return MFI.getStackSize() != 0;
}
- return frameTriviallyRequiresSP(MFI) || MFI.isFrameAddressTaken() ||
+ return (frameTriviallyRequiresSP(MFI) &&
+ !MF.getInfo<SIMachineFunctionInfo>()->isChainFunction()) ||
+ MFI.isFrameAddressTaken() ||
MF.getSubtarget<GCNSubtarget>().getRegisterInfo()->hasStackRealignment(
MF) ||
mayReserveScratchForCWSR(MF) ||
diff --git a/llvm/test/CodeGen/AMDGPU/amdgpu-cs-chain-fp-nosave.ll b/llvm/test/CodeGen/AMDGPU/amdgpu-cs-chain-fp-nosave.ll
new file mode 100644
index 0000000000000..a2696fe160067
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/amdgpu-cs-chain-fp-nosave.ll
@@ -0,0 +1,360 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -mtriple=amdgcn -mcpu=gfx1200 -o - < %s 2>&1 | FileCheck %s
+
+; These situations are "special" in that they have an alloca not in the entry
+; block, which affects prolog/epilog generation.
+
+declare amdgpu_gfx void @foo()
+
+define amdgpu_cs_chain void @test_alloca() {
+; CHECK-LABEL: test_alloca:
+; CHECK: ; %bb.0: ; %.entry
+; CHECK-NEXT: s_wait_loadcnt_dscnt 0x0
+; CHECK-NEXT: s_wait_expcnt 0x0
+; CHECK-NEXT: s_wait_samplecnt 0x0
+; CHECK-NEXT: s_wait_bvhcnt 0x0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: v_mov_b32_e32 v0, 0
+; CHECK-NEXT: s_mov_b32 s32, 16
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_mov_b32 s0, s32
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_i32 s32, s0, 0x200
+; CHECK-NEXT: scratch_store_b32 off, v0, s0
+; CHECK-NEXT: s_endpgm
+.entry:
+ br label %SW_C
+
+SW_C: ; preds = %.entry
+ %v = alloca i32, i32 1, align 4, addrspace(5)
+ store i32 0, ptr addrspace(5) %v, align 4
+ ret void
+}
+
+define amdgpu_cs_chain void @test_alloca_var_uniform(i32 inreg %count) {
+; CHECK-LABEL: test_alloca_var_uniform:
+; CHECK: ; %bb.0: ; %.entry
+; CHECK-NEXT: s_wait_loadcnt_dscnt 0x0
+; CHECK-NEXT: s_wait_expcnt 0x0
+; CHECK-NEXT: s_wait_samplecnt 0x0
+; CHECK-NEXT: s_wait_bvhcnt 0x0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_lshl_b32 s0, s0, 2
+; CHECK-NEXT: v_mov_b32_e32 v0, 0
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_i32 s0, s0, 15
+; CHECK-NEXT: s_mov_b32 s32, 16
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_and_b32 s0, s0, -16
+; CHECK-NEXT: s_mov_b32 s1, s32
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_lshl_b32 s0, s0, 5
+; CHECK-NEXT: scratch_store_b32 off, v0, s1
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_i32 s32, s1, s0
+; CHECK-NEXT: s_endpgm
+.entry:
+ br label %SW_C
+
+SW_C: ; preds = %.entry
+ %v = alloca i32, i32 %count, align 4, addrspace(5)
+ store i32 0, ptr addrspace(5) %v, align 4
+ ret void
+}
+
+define amdgpu_cs_chain void @test_alloca_var(i32 %count) {
+; CHECK-LABEL: test_alloca_var:
+; CHECK: ; %bb.0: ; %.entry
+; CHECK-NEXT: s_wait_loadcnt_dscnt 0x0
+; CHECK-NEXT: s_wait_expcnt 0x0
+; CHECK-NEXT: s_wait_samplecnt 0x0
+; CHECK-NEXT: s_wait_bvhcnt 0x0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: v_lshl_add_u32 v0, v8, 2, 15
+; CHECK-NEXT: s_mov_b32 s1, exec_lo
+; CHECK-NEXT: s_mov_b32 s0, 0
+; CHECK-NEXT: s_mov_b32 s32, 16
+; CHECK-NEXT: s_delay_alu instid0(VALU_DEP_1)
+; CHECK-NEXT: v_dual_mov_b32 v0, 0 :: v_dual_and_b32 v1, -16, v0
+; CHECK-NEXT: .LBB2_1: ; =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_ctz_i32_b32 s2, s1
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_delay_alu instid0(VALU_DEP_1)
+; CHECK-NEXT: v_readlane_b32 s3, v1, s2
+; CHECK-NEXT: s_bitset0_b32 s1, s2
+; CHECK-NEXT: s_max_u32 s0, s0, s3
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_cmp_lg_u32 s1, 0
+; CHECK-NEXT: s_cbranch_scc1 .LBB2_1
+; CHECK-NEXT: ; %bb.2:
+; CHECK-NEXT: s_mov_b32 s1, s32
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: v_lshl_add_u32 v1, s0, 5, s1
+; CHECK-NEXT: scratch_store_b32 off, v0, s1
+; CHECK-NEXT: v_readfirstlane_b32 s32, v1
+; CHECK-NEXT: s_endpgm
+.entry:
+ br label %SW_C
+
+SW_C: ; preds = %.entry
+ %v = alloca i32, i32 %count, align 4, addrspace(5)
+ store i32 0, ptr addrspace(5) %v, align 4
+ ret void
+}
+
+define amdgpu_cs_chain void @test_alloca_and_call() {
+; CHECK-LABEL: test_alloca_and_call:
+; CHECK: ; %bb.0: ; %.entry
+; CHECK-NEXT: s_wait_loadcnt_dscnt 0x0
+; CHECK-NEXT: s_wait_expcnt 0x0
+; CHECK-NEXT: s_wait_samplecnt 0x0
+; CHECK-NEXT: s_wait_bvhcnt 0x0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_getpc_b64 s[0:1]
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_sext_i32_i16 s1, s1
+; CHECK-NEXT: s_add_co_u32 s0, s0, foo@gotpcrel32@lo+12
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_ci_u32 s1, s1, foo@gotpcrel32@hi+24
+; CHECK-NEXT: v_mov_b32_e32 v0, 0
+; CHECK-NEXT: s_load_b64 s[0:1], s[0:1], 0x0
+; CHECK-NEXT: s_mov_b32 s32, 16
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_mov_b32 s2, s32
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_i32 s32, s2, 0x200
+; CHECK-NEXT: scratch_store_b32 off, v0, s2
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_swappc_b64 s[30:31], s[0:1]
+; CHECK-NEXT: s_endpgm
+.entry:
+ br label %SW_C
+
+SW_C: ; preds = %.entry
+ %v = alloca i32, i32 1, align 4, addrspace(5)
+ store i32 0, ptr addrspace(5) %v, align 4
+ call amdgpu_gfx void @foo()
+ ret void
+}
+
+define amdgpu_cs_chain void @test_alloca_and_call_var_uniform(i32 inreg %count) {
+; CHECK-LABEL: test_alloca_and_call_var_uniform:
+; CHECK: ; %bb.0: ; %.entry
+; CHECK-NEXT: s_wait_loadcnt_dscnt 0x0
+; CHECK-NEXT: s_wait_expcnt 0x0
+; CHECK-NEXT: s_wait_samplecnt 0x0
+; CHECK-NEXT: s_wait_bvhcnt 0x0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_getpc_b64 s[2:3]
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_sext_i32_i16 s3, s3
+; CHECK-NEXT: s_add_co_u32 s2, s2, foo@gotpcrel32@lo+12
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_ci_u32 s3, s3, foo@gotpcrel32@hi+24
+; CHECK-NEXT: s_lshl_b32 s0, s0, 2
+; CHECK-NEXT: s_load_b64 s[2:3], s[2:3], 0x0
+; CHECK-NEXT: s_add_co_i32 s0, s0, 15
+; CHECK-NEXT: v_mov_b32_e32 v0, 0
+; CHECK-NEXT: s_mov_b32 s32, 16
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_and_b32 s0, s0, -16
+; CHECK-NEXT: s_mov_b32 s1, s32
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_lshl_b32 s0, s0, 5
+; CHECK-NEXT: scratch_store_b32 off, v0, s1
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_i32 s32, s1, s0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_swappc_b64 s[30:31], s[2:3]
+; CHECK-NEXT: s_endpgm
+.entry:
+ br label %SW_C
+
+SW_C: ; preds = %.entry
+ %v = alloca i32, i32 %count, align 4, addrspace(5)
+ store i32 0, ptr addrspace(5) %v, align 4
+ call amdgpu_gfx void @foo()
+ ret void
+}
+
+define amdgpu_cs_chain void @test_alloca_and_call_var(i32 %count) {
+; CHECK-LABEL: test_alloca_and_call_var:
+; CHECK: ; %bb.0: ; %.entry
+; CHECK-NEXT: s_wait_loadcnt_dscnt 0x0
+; CHECK-NEXT: s_wait_expcnt 0x0
+; CHECK-NEXT: s_wait_samplecnt 0x0
+; CHECK-NEXT: s_wait_bvhcnt 0x0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: v_lshl_add_u32 v0, v8, 2, 15
+; CHECK-NEXT: s_mov_b32 s1, exec_lo
+; CHECK-NEXT: s_mov_b32 s0, 0
+; CHECK-NEXT: s_mov_b32 s32, 16
+; CHECK-NEXT: s_delay_alu instid0(VALU_DEP_1)
+; CHECK-NEXT: v_dual_mov_b32 v0, 0 :: v_dual_and_b32 v1, -16, v0
+; CHECK-NEXT: .LBB5_1: ; =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_ctz_i32_b32 s2, s1
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_delay_alu instid0(VALU_DEP_1)
+; CHECK-NEXT: v_readlane_b32 s3, v1, s2
+; CHECK-NEXT: s_bitset0_b32 s1, s2
+; CHECK-NEXT: s_max_u32 s0, s0, s3
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_cmp_lg_u32 s1, 0
+; CHECK-NEXT: s_cbranch_scc1 .LBB5_1
+; CHECK-NEXT: ; %bb.2:
+; CHECK-NEXT: s_getpc_b64 s[2:3]
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_sext_i32_i16 s3, s3
+; CHECK-NEXT: s_add_co_u32 s2, s2, foo@gotpcrel32@lo+12
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_ci_u32 s3, s3, foo@gotpcrel32@hi+24
+; CHECK-NEXT: s_mov_b32 s1, s32
+; CHECK-NEXT: s_load_b64 s[2:3], s[2:3], 0x0
+; CHECK-NEXT: v_lshl_add_u32 v1, s0, 5, s1
+; CHECK-NEXT: scratch_store_b32 off, v0, s1
+; CHECK-NEXT: v_readfirstlane_b32 s32, v1
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_wait_alu 0xf1ff
+; CHECK-NEXT: s_swappc_b64 s[30:31], s[2:3]
+; CHECK-NEXT: s_endpgm
+.entry:
+ br label %SW_C
+
+SW_C: ; preds = %.entry
+ %v = alloca i32, i32 %count, align 4, addrspace(5)
+ store i32 0, ptr addrspace(5) %v, align 4
+ call amdgpu_gfx void @foo()
+ ret void
+}
+
+define amdgpu_cs_chain void @test_call_and_alloca() {
+; CHECK-LABEL: test_call_and_alloca:
+; CHECK: ; %bb.0: ; %.entry
+; CHECK-NEXT: s_wait_loadcnt_dscnt 0x0
+; CHECK-NEXT: s_wait_expcnt 0x0
+; CHECK-NEXT: s_wait_samplecnt 0x0
+; CHECK-NEXT: s_wait_bvhcnt 0x0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_getpc_b64 s[0:1]
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_sext_i32_i16 s1, s1
+; CHECK-NEXT: s_add_co_u32 s0, s0, foo@gotpcrel32@lo+12
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_ci_u32 s1, s1, foo@gotpcrel32@hi+24
+; CHECK-NEXT: s_mov_b32 s32, 16
+; CHECK-NEXT: s_load_b64 s[0:1], s[0:1], 0x0
+; CHECK-NEXT: s_mov_b32 s4, s32
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_i32 s32, s4, 0x200
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_swappc_b64 s[30:31], s[0:1]
+; CHECK-NEXT: v_mov_b32_e32 v0, 0
+; CHECK-NEXT: scratch_store_b32 off, v0, s4
+; CHECK-NEXT: s_endpgm
+.entry:
+ br label %SW_C
+
+SW_C: ; preds = %.entry
+ %v = alloca i32, i32 1, align 4, addrspace(5)
+ call amdgpu_gfx void @foo()
+ store i32 0, ptr addrspace(5) %v, align 4
+ ret void
+}
+
+define amdgpu_cs_chain void @test_call_and_alloca_var_uniform(i32 inreg %count) {
+; CHECK-LABEL: test_call_and_alloca_var_uniform:
+; CHECK: ; %bb.0: ; %.entry
+; CHECK-NEXT: s_wait_loadcnt_dscnt 0x0
+; CHECK-NEXT: s_wait_expcnt 0x0
+; CHECK-NEXT: s_wait_samplecnt 0x0
+; CHECK-NEXT: s_wait_bvhcnt 0x0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_getpc_b64 s[2:3]
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_sext_i32_i16 s3, s3
+; CHECK-NEXT: s_add_co_u32 s2, s2, foo@gotpcrel32@lo+12
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_ci_u32 s3, s3, foo@gotpcrel32@hi+24
+; CHECK-NEXT: s_lshl_b32 s0, s0, 2
+; CHECK-NEXT: s_load_b64 s[2:3], s[2:3], 0x0
+; CHECK-NEXT: s_add_co_i32 s0, s0, 15
+; CHECK-NEXT: s_mov_b32 s32, 16
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_and_b32 s0, s0, -16
+; CHECK-NEXT: s_mov_b32 s4, s32
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_lshl_b32 s0, s0, 5
+; CHECK-NEXT: v_mov_b32_e32 v40, 0
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_i32 s32, s4, s0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_swappc_b64 s[30:31], s[2:3]
+; CHECK-NEXT: scratch_store_b32 off, v40, s4
+; CHECK-NEXT: s_endpgm
+.entry:
+ br label %SW_C
+
+SW_C: ; preds = %.entry
+ %v = alloca i32, i32 %count, align 4, addrspace(5)
+ call amdgpu_gfx void @foo()
+ store i32 0, ptr addrspace(5) %v, align 4
+ ret void
+}
+
+define amdgpu_cs_chain void @test_call_and_alloca_var(i32 %count) {
+; CHECK-LABEL: test_call_and_alloca_var:
+; CHECK: ; %bb.0: ; %.entry
+; CHECK-NEXT: s_wait_loadcnt_dscnt 0x0
+; CHECK-NEXT: s_wait_expcnt 0x0
+; CHECK-NEXT: s_wait_samplecnt 0x0
+; CHECK-NEXT: s_wait_bvhcnt 0x0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: v_lshl_add_u32 v0, v8, 2, 15
+; CHECK-NEXT: v_mov_b32_e32 v40, 0
+; CHECK-NEXT: s_mov_b32 s1, exec_lo
+; CHECK-NEXT: s_mov_b32 s0, 0
+; CHECK-NEXT: s_mov_b32 s32, 16
+; CHECK-NEXT: v_and_b32_e32 v0, -16, v0
+; CHECK-NEXT: .LBB8_1: ; =>This Inner Loop Header: Depth=1
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_ctz_i32_b32 s2, s1
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_delay_alu instid0(VALU_DEP_1)
+; CHECK-NEXT: v_readlane_b32 s3, v0, s2
+; CHECK-NEXT: s_bitset0_b32 s1, s2
+; CHECK-NEXT: s_max_u32 s0, s0, s3
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_cmp_lg_u32 s1, 0
+; CHECK-NEXT: s_cbranch_scc1 .LBB8_1
+; CHECK-NEXT: ; %bb.2:
+; CHECK-NEXT: s_getpc_b64 s[2:3]
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_sext_i32_i16 s3, s3
+; CHECK-NEXT: s_add_co_u32 s2, s2, foo@gotpcrel32@lo+12
+; CHECK-NEXT: s_wait_alu 0xfffe
+; CHECK-NEXT: s_add_co_ci_u32 s3, s3, foo@gotpcrel32@hi+24
+; CHECK-NEXT: s_mov_b32 s4, s32
+; CHECK-NEXT: s_load_b64 s[2:3], s[2:3], 0x0
+; CHECK-NEXT: v_lshl_add_u32 v0, s0, 5, s4
+; CHECK-NEXT: s_delay_alu instid0(VALU_DEP_1)
+; CHECK-NEXT: v_readfirstlane_b32 s32, v0
+; CHECK-NEXT: s_wait_kmcnt 0x0
+; CHECK-NEXT: s_wait_alu 0xf1ff
+; CHECK-NEXT: s_swappc_b64 s[30:31], s[2:3]
+; CHECK-NEXT: scratch_store_b32 off, v40, s4
+; CHECK-NEXT: s_endpgm
+.entry:
+ br label %SW_C
+
+SW_C: ; preds = %.entry
+ %v = alloca i32, i32 %count, align 4, addrspace(5)
+ call amdgpu_gfx void @foo()
+ store i32 0, ptr addrspace(5) %v, align 4
+ ret void
+}
|
arsenm
reviewed
Oct 10, 2025
| br label %SW_C | ||
|
|
||
| SW_C: ; preds = %.entry | ||
| %v = alloca i32, i32 %count, align 4, addrspace(5) |
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Does the out-of-blockness actually matter? Will any dynamic alloca do? The static sized allocas out of block are treated the same
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Does the out-of-blockness actually matter?
yes. Have a look at the definition of AllocaInst::isStaticAlloca():
llvm-project/llvm/lib/IR/Instructions.cpp
Lines 1300 to 1310 in 7314565
tldr: If it's not in the entry block, it's not static.
That makes MFI.hasVarSizedObjects true, which makes frameTriviallyRequiresSP (in SIFrameLowering.cpp) true, which makes SIFrameLowering::hasFPImpl true, which makes hasFP in SIFrameLowering::emitPrologue true.
And then, this becomes an issue:
llvm-project/llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
Lines 1327 to 1330 in 1389980
Contributor
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Afaiu, cs_chain functions are not supposed to return, btw. So, in general, there is no point in doing FP/SP saving stuff
Contributor
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I think the point is that you can keep the variable-sized allocas in the entry block.
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Ah, I misunderstood the comment, thanks, done
Co-authored-by: Matt Arsenault <[email protected]>
Contributor
Author
|
@arsenm do you have any further comments? |
Collaborator
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/88/builds/17815 Here is the relevant piece of the build log for the reference |
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|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/18/builds/22460 Here is the relevant piece of the build log for the reference |
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(both failures unrelated, the buildbots are already green again) |
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In case there is an dynamic alloca / an alloca which is not in the entry block, cs.chain functions do not set up an FP, but are reported to need one. This results in a failed assertion in
SIFrameLowering::emitPrologue()(Assertion(!HasFP || FPSaved) && "Needed to save FP but didn't save it anywhere"' failed.) This commit changeshasFPImpl` so that the need for an SP in a cs.chain function does not directly imply the need for an FP anymore.This LLVM defect was identified via the AMD Fuzzing project.
Re-opens #132711