[AMDGPU] Add image_atomic_fmin/fmax as aliases for GFX12 (llvm#107242)

This just follows SP3.

Author: jayfoad

llvm/lib/Target/AMDGPU/MIMGInstructions.td

@@ -1675,6 +1675,10 @@ defm IMAGE_ATOMIC_PK_ADD_BF16   : MIMG_Atomic <mimgopc<0x87, MIMG.NOP, MIMG.NOP,
 defm IMAGE_ATOMIC_ADD_FLT       : MIMG_Atomic <mimgopc<0x83, MIMG.NOP, MIMG.NOP, MIMG.NOP>, "image_atomic_add_flt", 0, 1>;
 defm IMAGE_ATOMIC_MIN_FLT       : MIMG_Atomic <mimgopc<0x84, MIMG.NOP, MIMG.NOP, MIMG.NOP>, "image_atomic_min_num_flt", 0, 1, "image_atomic_min_flt">;
 defm IMAGE_ATOMIC_MAX_FLT       : MIMG_Atomic <mimgopc<0x85, MIMG.NOP, MIMG.NOP, MIMG.NOP>, "image_atomic_max_num_flt", 0, 1, "image_atomic_max_flt">;
+let AssemblerPredicate = isGFX12Plus in {
+  def : AMDGPUMnemonicAlias<"image_atomic_fmin", "image_atomic_min_flt">;
+  def : AMDGPUMnemonicAlias<"image_atomic_fmax", "image_atomic_max_flt">;
+}
 
 defm IMAGE_SAMPLE               : MIMG_Sampler_WQM <mimgopc<0x1b, 0x1b, 0x20>, AMDGPUSample>;
 let OtherPredicates = [HasImageInsts, HasExtendedImageInsts] in {

llvm/test/MC/AMDGPU/gfx12_asm_vimage_alias.s

@@ -29,3 +29,9 @@ image_atomic_min_num_flt v0, v0, s[0:7] dmask:0x1 dim:SQ_RSRC_IMG_1D
 
 image_atomic_max_num_flt v0, v0, s[0:7] dmask:0x1 dim:SQ_RSRC_IMG_1D
 // GFX12: image_atomic_max_flt v0, v0, s[0:7] dmask:0x1 dim:SQ_RSRC_IMG_1D ; encoding: [0x00,0x40,0x61,0xd0,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00]
+
+image_atomic_fmin v0, v0, s[0:7] dmask:0x1 dim:SQ_RSRC_IMG_1D
+// GFX12: image_atomic_min_flt v0, v0, s[0:7] dmask:0x1 dim:SQ_RSRC_IMG_1D ; encoding: [0x00,0x00,0x61,0xd0,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00]
+
+image_atomic_fmax v0, v0, s[0:7] dmask:0x1 dim:SQ_RSRC_IMG_1D
+// GFX12: image_atomic_max_flt v0, v0, s[0:7] dmask:0x1 dim:SQ_RSRC_IMG_1D ; encoding: [0x00,0x40,0x61,0xd0,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00]