From 2c8936fd264239db1438358fc01c83412aa161ed Mon Sep 17 00:00:00 2001
From: Matt Arsenault <Matthew.Arsenault@amd.com>
Date: Fri, 3 May 2019 13:42:56 +0000
Subject: [PATCH] AMDGPU: Fix incorrect commute with sub when folding
 immediates

When a fold of an immediate into a sub/subrev required shrinking the
instruction, the wrong VOP2 opcode was used. This was using the VOP2
equivalent of the original instruction, not the commuted instruction
with the inverted opcode.

llvm-svn: 359883
---
 llvm/lib/Target/AMDGPU/SIFoldOperands.cpp        |  5 ++++-
 .../AMDGPU/fold-immediate-operand-shrink.mir     | 16 ++++++++--------
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
index 75d201245b8d..8db2ee216032 100644
--- a/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
+++ b/llvm/lib/Target/AMDGPU/SIFoldOperands.cpp
@@ -372,7 +372,10 @@ static bool tryAddToFoldList(SmallVectorImpl<FoldCandidate> &FoldList,
 
         assert(MI->getOperand(1).isDef());
 
-        int Op32 =  AMDGPU::getVOPe32(Opc);
+        // Make sure to get the 32-bit version of the commuted opcode.
+        unsigned MaybeCommutedOpc = MI->getOpcode();
+        int Op32 = AMDGPU::getVOPe32(MaybeCommutedOpc);
+
         FoldList.push_back(FoldCandidate(MI, CommuteOpNo, OpToFold, true,
                                          Op32));
         return true;
diff --git a/llvm/test/CodeGen/AMDGPU/fold-immediate-operand-shrink.mir b/llvm/test/CodeGen/AMDGPU/fold-immediate-operand-shrink.mir
index 1abd98c7a81e..5e58210571dc 100644
--- a/llvm/test/CodeGen/AMDGPU/fold-immediate-operand-shrink.mir
+++ b/llvm/test/CodeGen/AMDGPU/fold-immediate-operand-shrink.mir
@@ -250,8 +250,8 @@ body:             |
     ; GCN-LABEL: name: shrink_scalar_imm_vgpr_v_sub_i32_e64_no_carry_out_use
     ; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32_xm0 = S_MOV_B32 12345
     ; GCN: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
-    ; GCN: [[V_SUBREV_I32_e32_:%[0-9]+]]:vgpr_32 = V_SUBREV_I32_e32 [[S_MOV_B32_]], [[DEF]], implicit-def $vcc, implicit $exec
-    ; GCN: S_ENDPGM 0, implicit [[V_SUBREV_I32_e32_]]
+    ; GCN: [[V_SUB_I32_e32_:%[0-9]+]]:vgpr_32 = V_SUB_I32_e32 [[S_MOV_B32_]], [[DEF]], implicit-def $vcc, implicit $exec
+    ; GCN: S_ENDPGM 0, implicit [[V_SUB_I32_e32_]]
     %0:sreg_32_xm0 = S_MOV_B32 12345
     %1:vgpr_32 = IMPLICIT_DEF
     %2:vgpr_32, %3:sreg_64 = V_SUB_I32_e64 %0, %1, 0, implicit $exec
@@ -269,8 +269,8 @@ body:             |
     ; GCN-LABEL: name: shrink_vgpr_scalar_imm_v_sub_i32_e64_no_carry_out_use
     ; GCN: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
     ; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32_xm0 = S_MOV_B32 12345
-    ; GCN: [[V_SUB_I32_e32_:%[0-9]+]]:vgpr_32 = V_SUB_I32_e32 [[S_MOV_B32_]], [[DEF]], implicit-def $vcc, implicit $exec
-    ; GCN: S_ENDPGM 0, implicit [[V_SUB_I32_e32_]]
+    ; GCN: [[V_SUBREV_I32_e32_:%[0-9]+]]:vgpr_32 = V_SUBREV_I32_e32 [[S_MOV_B32_]], [[DEF]], implicit-def $vcc, implicit $exec
+    ; GCN: S_ENDPGM 0, implicit [[V_SUBREV_I32_e32_]]
     %0:vgpr_32 = IMPLICIT_DEF
     %1:sreg_32_xm0 = S_MOV_B32 12345
     %2:vgpr_32, %3:sreg_64 = V_SUB_I32_e64 %0, %1, 0, implicit $exec
@@ -288,8 +288,8 @@ body:             |
     ; GCN-LABEL: name: shrink_scalar_imm_vgpr_v_subrev_i32_e64_no_carry_out_use
     ; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32_xm0 = S_MOV_B32 12345
     ; GCN: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
-    ; GCN: [[V_SUB_I32_e32_:%[0-9]+]]:vgpr_32 = V_SUB_I32_e32 [[S_MOV_B32_]], [[DEF]], implicit-def $vcc, implicit $exec
-    ; GCN: S_ENDPGM 0, implicit [[V_SUB_I32_e32_]]
+    ; GCN: [[V_SUBREV_I32_e32_:%[0-9]+]]:vgpr_32 = V_SUBREV_I32_e32 [[S_MOV_B32_]], [[DEF]], implicit-def $vcc, implicit $exec
+    ; GCN: S_ENDPGM 0, implicit [[V_SUBREV_I32_e32_]]
     %0:sreg_32_xm0 = S_MOV_B32 12345
     %1:vgpr_32 = IMPLICIT_DEF
     %2:vgpr_32, %3:sreg_64 = V_SUBREV_I32_e64 %0, %1, 0, implicit $exec
@@ -307,8 +307,8 @@ body:             |
     ; GCN-LABEL: name: shrink_vgpr_scalar_imm_v_subrev_i32_e64_no_carry_out_use
     ; GCN: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
     ; GCN: [[S_MOV_B32_:%[0-9]+]]:sreg_32_xm0 = S_MOV_B32 12345
-    ; GCN: [[V_SUBREV_I32_e32_:%[0-9]+]]:vgpr_32 = V_SUBREV_I32_e32 [[S_MOV_B32_]], [[DEF]], implicit-def $vcc, implicit $exec
-    ; GCN: S_ENDPGM 0, implicit [[V_SUBREV_I32_e32_]]
+    ; GCN: [[V_SUB_I32_e32_:%[0-9]+]]:vgpr_32 = V_SUB_I32_e32 [[S_MOV_B32_]], [[DEF]], implicit-def $vcc, implicit $exec
+    ; GCN: S_ENDPGM 0, implicit [[V_SUB_I32_e32_]]
     %0:vgpr_32 = IMPLICIT_DEF
     %1:sreg_32_xm0 = S_MOV_B32 12345
     %2:vgpr_32, %3:sreg_64 = V_SUBREV_I32_e64 %0, %1, 0, implicit $exec