opt/spec_constants: fix bit pattern width checks. (#4588)

* test: add a test to show 8/16-bit

* opt/spec_constants: fix bit pattern width checks.

The input bit patterns are always at least 32-bits, so let the test
pass for 8/16-bit values as well. This shouldn't have any effect on the
64-bit patterns I assume this was introduced for.

source/opt/set_spec_constant_default_value_pass.cpp

@@ -98,11 +98,15 @@ std::vector<uint32_t> ParseDefaultValueBitPattern(
     }
     return result;
   } else if (const auto* IT = type->AsInteger()) {
-    if (IT->width() == input_bit_pattern.size() * sizeof(uint32_t) * 8) {
+    auto width = IT->width();
+    if (width == 8 || width == 16) width = 32;
+    if (width == input_bit_pattern.size() * sizeof(uint32_t) * 8) {
       return std::vector<uint32_t>(input_bit_pattern);
     }
   } else if (const auto* FT = type->AsFloat()) {
-    if (FT->width() == input_bit_pattern.size() * sizeof(uint32_t) * 8) {
+    auto width = FT->width();
+    if (width == 8 || width == 16) width = 32;
+    if (width == input_bit_pattern.size() * sizeof(uint32_t) * 8) {
       return std::vector<uint32_t>(input_bit_pattern);
     }
   }

test/opt/set_spec_const_default_value_test.cpp

@@ -935,6 +935,50 @@ INSTANTIATE_TEST_SUITE_P(
             "%2 = OpSpecConstantTrue %bool\n"
             "%3 = OpSpecConstantTrue %bool\n",
         },
+        // 19. 16-bit int type.
+        {
+            // code
+            "OpDecorate %1 SpecId 100\n"
+            "OpDecorate %2 SpecId 101\n"
+            "OpDecorate %3 SpecId 102\n"
+            "%short = OpTypeInt 16 1\n"
+            "%1 = OpSpecConstant %short 10\n"
+            "%2 = OpSpecConstant %short 11\n"
+            "%3 = OpSpecConstant %short 11\n",
+            // default values
+            SpecIdToValueBitPatternMap{
+                {100, {32768}}, {101, {0xffff}}, {102, {0xffffffd6}}},
+            // expected
+            "OpDecorate %1 SpecId 100\n"
+            "OpDecorate %2 SpecId 101\n"
+            "OpDecorate %3 SpecId 102\n"
+            "%short = OpTypeInt 16 1\n"
+            "%1 = OpSpecConstant %short 32768\n"
+            "%2 = OpSpecConstant %short 65535\n"
+            "%3 = OpSpecConstant %short -42\n",
+        },
+        // 20. 8-bit int type.
+        {
+            // code
+            "OpDecorate %1 SpecId 100\n"
+            "OpDecorate %2 SpecId 101\n"
+            "OpDecorate %3 SpecId 102\n"
+            "%char = OpTypeInt 8 1\n"
+            "%1 = OpSpecConstant %char 10\n"
+            "%2 = OpSpecConstant %char 11\n"
+            "%3 = OpSpecConstant %char 11\n",
+            // default values
+            SpecIdToValueBitPatternMap{
+                {100, {128}}, {101, {129}}, {102, {0xffffffd6}}},
+            // expected
+            "OpDecorate %1 SpecId 100\n"
+            "OpDecorate %2 SpecId 101\n"
+            "OpDecorate %3 SpecId 102\n"
+            "%char = OpTypeInt 8 1\n"
+            "%1 = OpSpecConstant %char 128\n"
+            "%2 = OpSpecConstant %char 129\n"
+            "%3 = OpSpecConstant %char -42\n",
+        },
     }));
 
 INSTANTIATE_TEST_SUITE_P(