AMDGPU: Figure out required AGPR count for inline asmusers/arsenm/amdgpu/parse-num-regs-asm-attributor

For now just try to compute the minimum number of AGPRs required
to allocate the asm. Leave the attributor changes to turn this
into an integer value for later.

2 files changed, 251 insertions, 7 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUAttributor.cpp b/llvm/lib/Target/AMDGPU/AMDGPUAttributor.cpp
index 59cc1df..1f5634a 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPUAttributor.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPUAttributor.cpp
@@ -1200,16 +1200,61 @@ AAAMDWavesPerEU &AAAMDWavesPerEU::createForPosition(const IRPosition &IRP,
   llvm_unreachable("AAAMDWavesPerEU is only valid for function position");
 }
 
-static bool inlineAsmUsesAGPRs(const InlineAsm *IA) {
-  for (const auto &CI : IA->ParseConstraints()) {
+/// Compute the minimum number of AGPRs required to allocate the inline asm.
+static unsigned inlineAsmGetNumRequiredAGPRs(const InlineAsm *IA,
+                                             const CallBase &Call) {
+  unsigned ArgNo = 0;
+  unsigned ResNo = 0;
+  unsigned AGPRDefCount = 0;
+  unsigned AGPRUseCount = 0;
+  unsigned MaxPhysReg = 0;
+  const DataLayout &DL = Call.getFunction()->getParent()->getDataLayout();
+
+  for (const InlineAsm::ConstraintInfo &CI : IA->ParseConstraints()) {
+    Type *Ty = nullptr;
+    switch (CI.Type) {
+    case InlineAsm::isOutput: {
+      Ty = Call.getType();
+      if (auto *STy = dyn_cast<StructType>(Ty))
+        Ty = STy->getElementType(ResNo);
+      ++ResNo;
+      break;
+    }
+    case InlineAsm::isInput: {
+      Ty = Call.getArgOperand(ArgNo++)->getType();
+      break;
+    }
+    case InlineAsm::isLabel:
+      continue;
+    case InlineAsm::isClobber:
+      // Parse the physical register reference.
+      break;
+    }
+
     for (StringRef Code : CI.Codes) {
-      Code.consume_front("{");
-      if (Code.starts_with("a"))
-        return true;
+      if (Code.starts_with("a")) {
+        // Virtual register, compute number of registers based on the type.
+        //
+        // We ought to be going through TargetLowering to get the number of
+        // registers, but we should avoid the dependence on CodeGen here.
+        unsigned RegCount = divideCeil(DL.getTypeSizeInBits(Ty), 32);
+        if (CI.Type == InlineAsm::isOutput) {
+          AGPRDefCount += RegCount;
+          if (CI.isEarlyClobber)
+            AGPRUseCount += RegCount;
+        } else
+          AGPRUseCount += RegCount;
+      } else {
+        // Physical register reference
+        auto [Kind, RegIdx, NumRegs] = AMDGPU::parseAsmConstraintPhysReg(Code);
+        if (Kind == 'a')
+          MaxPhysReg = std::max(MaxPhysReg, std::min(RegIdx + NumRegs, 256u));
+      }
     }
   }
 
-  return false;
+  unsigned MaxVirtReg = std::max(AGPRUseCount, AGPRDefCount);
+  return std::min(MaxVirtReg + MaxPhysReg, 256u);
 }
 
 // TODO: Migrate to range merge of amdgpu-agpr-alloc.
@@ -1251,7 +1296,7 @@ struct AAAMDGPUNoAGPR
       const Function *Callee = dyn_cast<Function>(CalleeOp);
       if (!Callee) {
         if (const InlineAsm *IA = dyn_cast<InlineAsm>(CalleeOp))
-          return !inlineAsmUsesAGPRs(IA);
+          return inlineAsmGetNumRequiredAGPRs(IA, CB) == 0;
         return false;
       }
 
diff --git a/llvm/test/CodeGen/AMDGPU/amdgpu-attributor-no-agpr.ll b/llvm/test/CodeGen/AMDGPU/amdgpu-attributor-no-agpr.ll
index 181dab8..e502995 100644
--- a/llvm/test/CodeGen/AMDGPU/amdgpu-attributor-no-agpr.ll
+++ b/llvm/test/CodeGen/AMDGPU/amdgpu-attributor-no-agpr.ll
@@ -251,6 +251,205 @@ define amdgpu_kernel void @indirect_calls_none_agpr(i1 %cond) {
   ret void
 }
 
+define amdgpu_kernel void @kernel_uses_asm_virtreg_def_struct_0() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_virtreg_def_struct_0(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call { i32, i32 } asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call {i32, i32} asm sideeffect "; def $0", "=a,=a"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_virtreg_use_struct_1() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_virtreg_use_struct_1(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call { i32, <2 x i32> } asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call {i32, <2 x i32>} asm sideeffect "; def $0", "=a,=a"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_virtreg_use_struct_2() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_virtreg_use_struct_2(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call { i32, <2 x i32> } asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call {i32, <2 x i32>} asm sideeffect "; def $0", "=a,=v"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_virtreg_ptr_ty() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_virtreg_ptr_ty(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; use $0", "a"(ptr poison)
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_virtreg_def_ptr_ty() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_virtreg_def_ptr_ty(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call ptr asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call ptr asm sideeffect "; def $0", "=a"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_virtreg_def_vector_ptr_ty() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_virtreg_def_vector_ptr_ty(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call <2 x ptr> asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call <2 x ptr> asm sideeffect "; def $0", "=a"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_physreg_def_struct_0() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_physreg_def_struct_0(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call { i32, i32 } asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call {i32, i32} asm sideeffect "; def $0", "={a0},={a[4:5]}"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_clobber() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_clobber(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; clobber $0", "~{a4}"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_clobber_tuple() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_clobber_tuple(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; clobber $0", "~{a[10:13]}"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_clobber_oob() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_clobber_oob(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; clobber $0", "~{a256}"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_clobber_max() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_clobber_max(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; clobber $0", "~{a255}"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_physreg_oob() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_physreg_oob(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; use $0", "{a256}"(i32 poison)
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_virtreg_def_max_ty() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_virtreg_def_max_ty(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call <32 x i32> asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call <32 x i32> asm sideeffect "; def $0", "=a"()
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_virtreg_use_max_ty() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_virtreg_use_max_ty(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; use $0", "a"(<32 x i32> poison)
+  ret void
+}
+
+define amdgpu_kernel void @kernel_uses_asm_virtreg_use_def_max_ty() {
+; CHECK-LABEL: define amdgpu_kernel void @kernel_uses_asm_virtreg_use_def_max_ty(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call <32 x i32> asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call <32 x i32> asm sideeffect "; use $0", "=a,a"(<32 x i32> poison)
+  ret void
+}
+
+define amdgpu_kernel void @vreg_use_exceeds_register_file() {
+; CHECK-LABEL: define amdgpu_kernel void @vreg_use_exceeds_register_file(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    call void asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  call void asm sideeffect "; use $0", "a"(<257 x i32> poison)
+  ret void
+}
+
+define amdgpu_kernel void @vreg_def_exceeds_register_file() {
+; CHECK-LABEL: define amdgpu_kernel void @vreg_def_exceeds_register_file(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call <257 x i32> asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call <257 x i32> asm sideeffect "; def $0", "=a"()
+  ret void
+}
+
+define amdgpu_kernel void @multiple() {
+; CHECK-LABEL: define amdgpu_kernel void @multiple(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call { <16 x i32>, <8 x i32>, <8 x i32> } asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call {<16 x i32>, <8 x i32>, <8 x i32>} asm sideeffect "; def $0", "=a,=a,=a,a,a,a"(<4 x i32> splat (i32 0), <8 x i32> splat (i32 1), i64 999)
+  ret void
+}
+
+define amdgpu_kernel void @earlyclobber_0() {
+; CHECK-LABEL: define amdgpu_kernel void @earlyclobber_0(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call <8 x i32> asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call <8 x i32> asm sideeffect "; def $0", "=&a,a"(i32 0)
+  ret void
+}
+
+define amdgpu_kernel void @earlyclobber_1() {
+; CHECK-LABEL: define amdgpu_kernel void @earlyclobber_1(
+; CHECK-SAME: ) #[[ATTR0]] {
+; CHECK-NEXT:    [[DEF:%.*]] = call { <8 x i32>, <16 x i32> } asm sideeffect "
+; CHECK-NEXT:    ret void
+;
+  %def = call { <8 x i32>, <16 x i32 > } asm sideeffect "; def $0, $1", "=&a,=&a,a,a"(i32 0, <16 x i32> splat (i32 1))
+  ret void
+}
 
 attributes #0 = { "amdgpu-agpr-alloc"="0" }
 ;.