Merge pull request #3819 from alyssarosenzweig/bug/rcr-smol

Fix 8/16-bit RCR

FEXCore/Source/Interface/Core/OpcodeDispatcher.cpp

@@ -2224,9 +2224,10 @@ void OpDispatchBuilder::RCRSmallerOp(OpcodeArgs) {
       Tmp = _Bfi(OpSize::i64Bit, 17, 34, Tmp, Tmp);
     }
 
-    // Entire bitfield has been setup
-    // Just extract the 8 or 16bits we need
-    Ref Res = _Lshr(OpSize::i32Bit, Tmp, Src);
+    // Entire bitfield has been setup. Just extract the 8 or 16bits we need.
+    // 64-bit shift used because we want to rotate in our cascaded upper bits
+    // rather than zeroes.
+    Ref Res = _Lshr(OpSize::i64Bit, Tmp, Src);
 
     StoreResult(GPRClass, Op, Res, -1);
 

unittests/ASM/FEX_bugs/LargeRotatesForSmallSizes.asm

@@ -0,0 +1,115 @@
+%ifdef CONFIG
+{
+  "RegData": {
+    "RAX": "0x4142434445464748",
+    "RBX": "0x4142434445464748",
+    "RCX": "0x4142434445464748",
+    "RDX": "0x4142434445464748",
+    "RSI": "0x4142434445464714",
+    "RDI": "0x414243444546478a",
+    "RBP": "0x4142434445464704",
+    "RSP": "0x414243444546478a",
+    "R8":  "0x4142434445461d22",
+    "R9":  "0x41424344454651d2",
+    "R10": "0x4142434445461d20",
+    "R11": "0x41424344454651d2",
+    "R12": "0x4142434445463a45",
+    "R13": "0x41424344454608e9",
+    "R14": "0x4142434445463a41",
+    "R15": "0x41424344454608e9"
+  }
+}
+%endif
+
+; FEX-Emu had a bug where 8-bit and 16-bit rotates with carry generated incorrect results when the rotate amount was larger than the data size.
+; This is well defined in x86 semantics.
+
+mov cl, 0x9
+stc
+jmp .test
+.test:
+; 8-bit: Test 1-bit past data size, plus carry
+rcr byte [rel .data + (0 * 8)], cl
+rcl byte [rel .data + (1 * 8)], cl
+
+mov cl, 0x9
+clc
+jmp .test2
+.test2:
+; 8-bit: Test 1-bit past data size, no carry
+rcr byte [rel .data + (2 * 8)], cl
+rcl byte [rel .data + (3 * 8)], cl
+
+mov cl, 0x1f
+stc
+jmp .test3
+.test3:
+; 8-bit: Test maximum 32-bit rotate, plus carry
+rcr byte [rel .data + (4 * 8)], cl
+rcl byte [rel .data + (5 * 8)], cl
+
+mov cl, 0x1f
+clc
+jmp .test4
+.test4:
+; 8-bit: Test maximum 32-bit rotate, plus carry
+rcr byte [rel .data + (6 * 8)], cl
+rcl byte [rel .data + (7 * 8)], cl
+
+mov cl, 0xF
+stc
+jmp .test5
+.test5:
+; 16-bit: Test 1-bit past data size, plus carry
+rcr word [rel .data + (8 * 8)], cl
+rcl word [rel .data + (9 * 8)], cl
+
+mov cl, 0xF
+clc
+jmp .test6
+.test6:
+; 16-bit: Test 1-bit past data size, no carry
+rcr word [rel .data + (10 * 8)], cl
+rcl word [rel .data + (11 * 8)], cl
+
+mov cl, 0x1f
+stc
+jmp .test7
+.test7:
+; 16-bit: Test maximum 32-bit rotate, plus carry
+rcr word [rel .data + (12 * 8)], cl
+rcl word [rel .data + (13 * 8)], cl
+
+mov cl, 0x1f
+clc
+jmp .test8
+.test8:
+; 16-bit: Test maximum 32-bit rotate, plus carry
+rcr word [rel .data + (14 * 8)], cl
+rcl word [rel .data + (15 * 8)], cl
+
+jmp .end
+.end:
+
+; Load all the results in order
+mov rax, [rel .data + (0 * 8)]
+mov rbx, [rel .data + (1 * 8)]
+mov rcx, [rel .data + (2 * 8)]
+mov rdx, [rel .data + (3 * 8)]
+mov rsi, [rel .data + (4 * 8)]
+mov rdi, [rel .data + (5 * 8)]
+mov rbp, [rel .data + (6 * 8)]
+mov rsp, [rel .data + (7 * 8)]
+mov r8,  [rel .data + (8 * 8)]
+mov r9,  [rel .data + (9 * 8)]
+mov r10, [rel .data + (10 * 8)]
+mov r11, [rel .data + (11 * 8)]
+mov r12, [rel .data + (12 * 8)]
+mov r13, [rel .data + (13 * 8)]
+mov r14, [rel .data + (14 * 8)]
+mov r15, [rel .data + (15 * 8)]
+
+hlt
+
+.data:
+times 16 dq 0x4142434445464748

unittests/InstructionCountCI/FlagM/PrimaryGroup.json

@@ -947,7 +947,7 @@
         "bfi x21, x21, #9, #9",
         "bfi x21, x21, #18, #18",
         "bfi x21, x21, #36, #9",
-        "lsr w20, w21, #2",
+        "lsr x20, x21, #2",
         "bfxil x4, x20, #0, #8",
         "rmif x21, #0, #nzCv"
       ]
@@ -1089,7 +1089,7 @@
         "bfi x21, x20, #16, #1",
         "bfi x21, x21, #17, #17",
         "bfi x21, x21, #34, #17",
-        "lsr w20, w21, #2",
+        "lsr x20, x21, #2",
         "bfxil x4, x20, #0, #16",
         "rmif x21, #0, #nzCv"
       ]
@@ -1613,7 +1613,7 @@
         "bfi x21, x21, #9, #9",
         "bfi x21, x21, #18, #18",
         "bfi x21, x21, #36, #9",
-        "lsr w20, w21, w5",
+        "lsr x20, x21, x5",
         "bfxil x4, x20, #0, #8",
         "sub w22, w5, #0x1 (1)",
         "lsr w21, w21, w22",
@@ -1840,7 +1840,7 @@
         "bfi x21, x20, #16, #1",
         "bfi x21, x21, #17, #17",
         "bfi x21, x21, #34, #17",
-        "lsr w20, w21, w5",
+        "lsr x20, x21, x5",
         "bfxil x4, x20, #0, #16",
         "sub w22, w5, #0x1 (1)",
         "lsr w21, w21, w22",

unittests/InstructionCountCI/PrimaryGroup.json

@@ -1043,7 +1043,7 @@
         "bfi x21, x21, #9, #9",
         "bfi x21, x21, #18, #18",
         "bfi x21, x21, #36, #9",
-        "lsr w20, w21, #2",
+        "lsr x20, x21, #2",
         "bfxil x4, x20, #0, #8",
         "ubfx x20, x21, #1, #1",
         "mrs x21, nzcv",
@@ -1222,7 +1222,7 @@
         "bfi x21, x20, #16, #1",
         "bfi x21, x21, #17, #17",
         "bfi x21, x21, #34, #17",
-        "lsr w20, w21, #2",
+        "lsr x20, x21, #2",
         "bfxil x4, x20, #0, #16",
         "ubfx x20, x21, #1, #1",
         "mrs x21, nzcv",
@@ -1900,7 +1900,7 @@
         "bfi x21, x21, #9, #9",
         "bfi x21, x21, #18, #18",
         "bfi x21, x21, #36, #9",
-        "lsr w20, w21, w5",
+        "lsr x20, x21, x5",
         "bfxil x4, x20, #0, #8",
         "sub w22, w5, #0x1 (1)",
         "lsr w21, w21, w22",
@@ -2175,7 +2175,7 @@
         "bfi x21, x20, #16, #1",
         "bfi x21, x21, #17, #17",
         "bfi x21, x21, #34, #17",
-        "lsr w20, w21, w5",
+        "lsr x20, x21, x5",
         "bfxil x4, x20, #0, #16",
         "sub w22, w5, #0x1 (1)",
         "lsr w21, w21, w22",