Follow-up: Use IRParser instead of BitcodeReader (#3405)

This is a follow-up of
KhronosGroup/SPIRV-LLVM-Translator#3399 .

After KhronosGroup/SPIRV-LLVM-Translator#3399,
we do not need to run `llvm-as`, we can directly consume the textual
llvm-ir representation.

This patch profits from this to clean this pattern in the test:
```bash
RUN: llvm-as %s -o %t.bc
RUN: llvm-spirv %t.bc ...
```
And replaces it by
```bash
RUN: llvm-spirv %s ...
```

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@57c254d32ea287a

Author: jmmartinez

llvm-spirv/test/DebugInfo/DebugInfoLexicalBlockDependency.ll

@@ -3,8 +3,7 @@
 ;   - The parent scope of the local variable VAL is the lexical block LB
 ;   - The parent scope of the lexical block LB is the subprogram.
 
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv %t.bc -o %t.spv
+; RUN: llvm-spirv %s -o %t.spv
 ; RUN: llvm-spirv -r %t.spv -o %t.rev.bc
 ; RUN: llvm-dis %t.rev.bc -o %t.rev.ll
 ; RUN: FileCheck %s --input-file %t.rev.ll

llvm-spirv/test/DebugInfo/NonSemantic/Shader200/DebugInfoStringType.ll

@@ -1,5 +1,4 @@
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv -spirv-text %t.bc -o %t.spt --spirv-debug-info-version=nonsemantic-shader-200
+; RUN: llvm-spirv -spirv-text %s -o %t.spt --spirv-debug-info-version=nonsemantic-shader-200
 ; RUN: FileCheck < %t.spt %s -check-prefix=CHECK-SPIRV
 ; RUN: llvm-spirv -to-binary %t.spt -o %t.spv
 

llvm-spirv/test/DebugInfo/NonSemantic/Shader200/DebugInfoSubrange.ll

@@ -1,5 +1,4 @@
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv -spirv-text %t.bc -o %t.spt --spirv-debug-info-version=nonsemantic-shader-200
+; RUN: llvm-spirv -spirv-text %s -o %t.spt --spirv-debug-info-version=nonsemantic-shader-200
 ; RUN: FileCheck < %t.spt %s -check-prefix=CHECK-SPIRV
 ; RUN: llvm-spirv -to-binary %t.spt -o %t.spv
 

llvm-spirv/test/DebugInfo/NonSemantic/Shader200/DebugInfoTargetFunction.ll

@@ -1,5 +1,4 @@
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv -spirv-text %t.bc -o %t.spt --spirv-debug-info-version=nonsemantic-shader-200
+; RUN: llvm-spirv -spirv-text %s -o %t.spt --spirv-debug-info-version=nonsemantic-shader-200
 ; RUN: FileCheck < %t.spt %s -check-prefix=CHECK-SPIRV
 ; RUN: llvm-spirv -to-binary %t.spt -o %t.spv
 

llvm-spirv/test/DebugInfo/NonSemantic/Shader200/InlineNamespace.ll

@@ -1,5 +1,4 @@
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv -spirv-text %t.bc -o %t.spt --spirv-debug-info-version=nonsemantic-shader-200
+; RUN: llvm-spirv -spirv-text %s -o %t.spt --spirv-debug-info-version=nonsemantic-shader-200
 ; RUN: FileCheck < %t.spt %s -check-prefix=CHECK-SPIRV
 ; RUN: llvm-spirv -to-binary %t.spt -o %t.spv
 

llvm-spirv/test/DebugInfo/OpenCL100/DebugInfoSubrange.ll

@@ -1,5 +1,4 @@
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv -spirv-text %t.bc -o %t.spt
+; RUN: llvm-spirv -spirv-text %s -o %t.spt
 ; RUN: FileCheck < %t.spt %s -check-prefix=CHECK-SPIRV
 
 ; RUN: llvm-spirv -to-binary %t.spt -o %t.spv

llvm-spirv/test/DebugInfo/RecursiveDebugInfo.ll

@@ -36,8 +36,7 @@
 ;    return 0;
 ;  }
 
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv %t.bc -o %t.spv
+; RUN: llvm-spirv %s -o %t.spv
 ; RUN: llvm-spirv -r %t.spv -o %t.rev.bc
 ; RUN: llvm-dis < %t.rev.bc | FileCheck %s
 

llvm-spirv/test/complex-constexpr-vector.ll

@@ -1,5 +1,4 @@
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv %t.bc -o %t.spv
+; RUN: llvm-spirv %s -o %t.spv
 ; RUN: llvm-spirv %t.spv -to-text -o %t.spt
 ; RUN: FileCheck < %t.spt %s --check-prefix=CHECK-SPIRV
 ; RUN: llvm-spirv -r %t.spv -o %t.rev.bc

llvm-spirv/test/complex-constexpr.ll

@@ -1,5 +1,5 @@
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv %t.bc -o %t.spv
+; RUN: llvm-spirv %s -o %t.spv
+; RUN: spirv-val %t.spv
 ; RUN: llvm-spirv %t.spv -o %t.spt --to-text
 ; RUN: llvm-spirv -r %t.spv -o %t.rev.bc
 ; RUN: llvm-dis %t.rev.bc

llvm-spirv/test/constexpr_phi.ll

@@ -1,5 +1,4 @@
-; RUN: llvm-as %s -o %t.bc
-; RUN: llvm-spirv %t.bc --spirv-ext=+SPV_INTEL_function_pointers -o %t.spv
+; RUN: llvm-spirv %s --spirv-ext=+SPV_INTEL_function_pointers -o %t.spv
 ; RUN: llvm-spirv %t.spv -to-text -o %t.spt
 ; RUN: FileCheck < %t.spt %s --check-prefix=CHECK-SPIRV
 ; RUN: llvm-spirv -r %t.spv -o %t.r.bc