[llvm] 78ec59e - [AMDGPU] Handle mandatory literals in isOperandLegal

[Jay Foad via llvm-commits]

Author: Jay Foad
Date: 2022-05-20T16:14:00+01:00
New Revision: 78ec59e6aea9c29f204877bacfa12d70c21289fc

URL: https://github.com/llvm/llvm-project/commit/78ec59e6aea9c29f204877bacfa12d70c21289fc
DIFF: https://github.com/llvm/llvm-project/commit/78ec59e6aea9c29f204877bacfa12d70c21289fc.diff

LOG: [AMDGPU] Handle mandatory literals in isOperandLegal

Extend SIInstrInfo::isOperandLegal to enforce a limit on the number of
literal operands for all VALU instructions, not just VOP3. In particular
it now handles VOP2 instructions with a mandatory literal operand like
V_FMAAK_F32.

Differential Revision: https://reviews.llvm.org/D126064

Added: 
    

Modified: 
    llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
    llvm/test/CodeGen/AMDGPU/fold-fmaak-bug.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
index 0b0f2c4a64b19..b23e884a5d0e1 100644
--- a/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
+++ b/llvm/lib/Target/AMDGPU/SIInstrInfo.cpp
@@ -4965,9 +4965,9 @@ bool SIInstrInfo::isOperandLegal(const MachineInstr &MI, unsigned OpIdx,
     MO = &MI.getOperand(OpIdx);
 
   int ConstantBusLimit = ST.getConstantBusLimit(MI.getOpcode());
-  int VOP3LiteralLimit = ST.hasVOP3Literal() ? 1 : 0;
+  int LiteralLimit = !isVOP3(MI) || ST.hasVOP3Literal() ? 1 : 0;
   if (isVALU(MI) && usesConstantBus(MRI, *MO, OpInfo)) {
-    if (isVOP3(MI) && isLiteralConstantLike(*MO, OpInfo) && !VOP3LiteralLimit--)
+    if (isLiteralConstantLike(*MO, OpInfo) && !LiteralLimit--)
       return false;
 
     SmallDenseSet<RegSubRegPair> SGPRsUsed;
@@ -4986,12 +4986,10 @@ bool SIInstrInfo::isOperandLegal(const MachineInstr &MI, unsigned OpIdx,
             return false;
           SGPRsUsed.insert(SGPR);
         }
-      } else if (InstDesc.OpInfo[i].OperandType == AMDGPU::OPERAND_KIMM32) {
-        if (--ConstantBusLimit <= 0)
-          return false;
-      } else if (isVOP3(MI) && AMDGPU::isSISrcOperand(InstDesc, i) &&
-                 isLiteralConstantLike(Op, InstDesc.OpInfo[i])) {
-        if (!VOP3LiteralLimit--)
+      } else if (InstDesc.OpInfo[i].OperandType == AMDGPU::OPERAND_KIMM32 ||
+                 (AMDGPU::isSISrcOperand(InstDesc, i) &&
+                  isLiteralConstantLike(Op, InstDesc.OpInfo[i]))) {
+        if (!LiteralLimit--)
           return false;
         if (--ConstantBusLimit <= 0)
           return false;

diff  --git a/llvm/test/CodeGen/AMDGPU/fold-fmaak-bug.ll b/llvm/test/CodeGen/AMDGPU/fold-fmaak-bug.ll
index 8ac8b6b427989..4af5b66bb1225 100644
--- a/llvm/test/CodeGen/AMDGPU/fold-fmaak-bug.ll
+++ b/llvm/test/CodeGen/AMDGPU/fold-fmaak-bug.ll
@@ -1,13 +1,12 @@
-; RUN: not --crash llc -march=amdgcn -mcpu=gfx1010 -verify-machineinstrs < %s 2>&1 | FileCheck %s -check-prefix GFX10
+; RUN: llc -march=amdgcn -mcpu=gfx1010 -verify-machineinstrs < %s | FileCheck %s -check-prefix GFX10
 
 declare <2 x half> @llvm.amdgcn.cvt.pkrtz(float, float)
 declare void @llvm.amdgcn.exp.compr.v2f16(i32 immarg, i32 immarg, <2 x half>, <2 x half>, i1 immarg, i1 immarg)
 
-; FIXME: This instruction uses two 
diff erent literal constants which is not
-; allowed.
+; Check that this constant is not folded into the v_fmaak_f32 instruction.
 ; GFX10-LABEL: _amdgpu_ps_main:
-; GFX10: Bad machine code: VOP2/VOP3 instruction uses more than one literal
-; GFX10: instruction: %4:vgpr_32 = nnan nsz arcp contract afn reassoc nofpexcept V_FMAAK_F32 1078530011, %0:vgpr_32, -1077342245, implicit $mode, implicit $exec
+; GFX10: v_mov_b32_e32 v1, 0x40490fdb
+; GFX10: v_fmaak_f32 v1, v0, v1, 0xbfc90fdb
 define amdgpu_ps void @_amdgpu_ps_main(float %arg) {
 bb:
   %i = fmul reassoc nnan nsz arcp contract afn float %arg, 0x400921FB60000000